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Chapter-1 Introduction

1

The chemistry of metal alkoxide dates back to 1840s when Liebig first time observed

the reaction of alcohol with metal like sodium and potassium In the same year the

term alkoxides was used by Kuhlmann1

for the alkaline derivatives of alcohols

Thereafter the chemistry of alkoxides has been the center of attraction for the

researchers due to their tremendous applicability especially in the fields like catalysis

sol-gel and MOCVD methods (metal-organic chemical vapor-phase deposition) for

synthesis of pure metal oxides precursors for nano materials ceramics etc

Alkoxides M(OR)n are compounds with one or more metal atoms or semi-metal atoms

(M) with alkoxy groups (OR) as ligands An alkoxy ligand is produced when

hydrogen atom is stripped from an alcohol (ROH) or by dividing an ether (ROR)

molecule in such way that oxygen is retained along with R group (ie OR) In other

words alkoxides may be regarded similar to hydroxides (MOH) in which the H has

been substituted by an alkyl or aryl group(R) The alkoxides are known for most of

the elements in the periodic table

Most of the metallic elements are reactive towards oxygen because an oxide exists in

stable single or mixed phases Molecular precursors derived from alkoxide complexes

can generate ceramic materials in a single step (thus-called single-source precursors ndash

SSPs)2

Metal alkoxides are very good single source molecular precursor (SSP) for

oxide synthesis This is mainly due to their molecular structure and high reactivity

which depends on the electronegativity of the metal ion ability to increase their

coordination numbers and the steric hindrance in the alkoxy groups This helps in the

synthesis of corresponding colloidal metal oxides with high homogeneity

There has been a growing interest in the development of the chemistry of mixed-metal

bi and polynuclear alkoxo and alkoxo-organometallic complexes for the last two

decades Motivation force for such interest derives from their fascinating structural

chemistry interesting catalytic properties and high potential for industrial

applications34

The important fact that most of the heterometallic alkoxo species can

generate bimetallic or multimetallic oxides has resulted in high research activity in the

field Their attractiveness lies in the fact that they are easily accessible and are

inexpensive Furthermore alkoxide ligands are easily removable via thermal

treatments Finally these compounds already have established metal-oxygen bonds It

is worth mentioning that their thermal deposition or decomposition processes can be

performed at relatively low temperatures compared to conventional methods


2

involving other inorganic salts These features make the metal oxides derived from

metal alkoxides highly pure with specific properties like high hardness chemical and

mechanical resistance and high temperature stability The softndashchemical approach is

a flexible simple and novel synthesis for industrial production Different types of

precursor can lead to change in unique features of the structural framework that

affects the physical and chemical properties in the final product by retaining the

stoichiometric ratio under control This will help to predict favorable morphology for

its futuristic applications with high reliability accuracy and reproducible results5-14

From above mention feature it is evident that metal alkoxides play the key role for

preparing materials of excellent functions and shapes

A range of catalytic applications of Group (IV) (ieTi Zrand Hf) is mainly due to the

Lewis acidic nature of M(IV) complexes Group (IV) elements are important

components of electro ceramics such as lead zirconium titanate (PZT) and barium

titanate Sol-gel processing of these and related materials is based upon hydrolysis of

alkoxide solutions It is found that the species produced when acetylacetone (acacH)

is added to Ti(OR)4 is 11 reaction product [Ti(OR)3(acac)] which is dimeric readily

under-go ligand redistribution in solution to give Ti(OR)4 and [Ti(OR)2(acac)2] 17

O

NMR spectroscopy has been used to investigate the hydrolysis of the resulting

mixture for R = Pri and the results were interpreted in terms of the hydrolysis behavior

of the individual mononuclear components Titanium complexes of alkoxide and

aryloxide ligands exhibit a rich coordination chemistry and reactivity and find

applications in various fields15

The interest in the development of non-metallocene

complexes for the polymerization of α-olefins16

has created a new range of chelating

dialkoxo17-24

ligands for group IV transition metals Complex formation may be

effected by the steric bulk on the ligands Furthermore the olefin polymerization

reactivity by a possible catalyst may strongly depend on the crowding around the

metal as substantial bulk on one hand may hinder the approach of an incoming

olefin and on the other hand decelerate termination processes25-28

Several types of

amine bis (phenolate) titanium complexes having different steric crowding around

the metal have been synthesized The [ONNO]-type ligands bind to the metal in a

tetradentate fashion leads to octahedral bis-(isopropoxide) complexes regardless of

the steric bulk of the aromatic ring substituents Various complexes involving

ethylenediamine and metal alkoxides with particular reference to complexes involving


3

titanium isopropoxide have been reported The alkoxides Titanium(IV) are

diamagnetic tetrahedral molecules and are being used in many organic synthesis

and in material science The structures of titanium alkoxides are often complex

Alkoxides derived from bulkier alcohols such as isopropanol aggregate less Titanium

isopropoxide is mainly a monomer in non- polar solvents Titanium isopropoxide is a

component of the Sharpless epoxidation a method used for the synthesis of chiral

epoxides Titanium isopropoxide is also used as a catalyst for the preparation of

certain cyclopropanes in the Kulinkovich29

reaction Prochiral thioethers are oxidized

enantio-selectively using a catalyst derived from Ti(OPri)4

The aluminium alkoxides chemistry has progressed significantly in the last fifty years

due to advances in their synthetic methodology and in the understanding of the role

ligands and co-ligands play in stabilizing the compounds and ensuring solubility

During column chromatography Aluminium oxide is well known as the stationary

phase It has also been used as solid support for various reactions including dehydro-

genation30

reactions with formic and acetic acid31

selective oxidation of alcohols to

carbonyl compounds using iodobenzene diacetate32

and aziridination and

cyclopropanation reactions using copper nanoparticles33

Aluminium alkoxides are thermally stable and even the insoluble [Al(OMe)3]n may be

sublimed at 240oC under reduced pressure The higher alkoxides are all soluble

Distillable products and the melting points of the solids increase with increasing

complexity of the alkyl chain Degree of association of aluminium alkoxides have

been reported by number of investigators rather widely based on molecular weight

determinations RCMehrotra34

revealed that freshly distilled aluminium isopropoxide

was trimeric in boiling benzene and it changed into a tetrameric form on ageing With

increasing branching of alkoxo groups the complexity diminished and it reduced to

the dimeric state in the tert-butoxide

Tris(acetylacetonato) aluminium(III)35

was the first complex to be obtained using a β-

diketone ligand Tris(β-diketonato) aluminium(III) complexes have then been

synthesized via a variety of routes as shown in Figure 1 Most frequently applied

Method is I which involves dissolution of the β-diketone in aqueous ammonia (if the

ligand is water-soluble) or a mixture of aqueous ammonia and methanol36

Aqueous

ammonia forms the ammonium salt by removing the methane proton from the β

diketone This is due to the acidity of the methine protons of β-diketones The


4

ammonium salt is then reacted with aluminium sulphate The reaction completes with

precipitation of product The synthesis of tris(ferrocenyl-13-butanedionate)

aluminium (III) by Zanello et al37

also take place via Method I This complex

[(FcCOCHCOCH3)3 Al] is the only known ferrocene containing β-diketonato

aluminium (III) complex

Method I Al2(SO4)3 + 3O

R1

O

R2

NH4

e-3(NH

4)2SO

4H2OCH

3OH

Al

O

O

R1

R2

3

3O

R1

O

R2

Method II AlCl3 +

3O

R1

O

R2

Method III Al(OH)3 +

(freshly prepared)

-3 HCl(g)

-3 H 2O(g)

EtOH

Figure 1 Methods commonly used for synthesis tris(β-diketonato aluminium(III)

complexes

Method II involves refluxing the β-diketone with aluminium chloride in benzene and

the reaction completes by the removal of gaseous HCl38

The method III shows that

the tris(β-diketonato) aluminium(III) complex can be synthesized from freshly

precipitated aluminium hydroxide34

This reaction thus illustrates that β-diketones is

acidic enough to attack freshly precipitated aluminium hydroxide

Due to existence of many hydrolysis species39

the aqueous chemistry of aluminium is

complex At low pH (25 - 35) 40

Tomany and co-workers performed an investigation

on the kinetics and mechanism of the reactions of aluminium (III) with acetylacetone

trifluoro actylacetone and hetpane-35-dione Aluminium alkoxide and the β-diketone

(Figure 2)3441

directly synthesized mixed alkoxy β-diketonato aluminium (III)

complexes of the type Al(R1COCHCO R

2)n(OR)3-n Driving force behind the reaction

is the azeotropic removal of the alcohol with benzene It is also interesting to note that

the alkoxide groups are significantly more reactive than the β-diketonate ligands

Another reason why the β-diketonate ligands displace the alkoxide is that bidentate


5

ligands (β-diketonates) form stronger bonds with the coordinating metal than

monodentate (alkoxide) ligands

AlH

O

O

R1

R2

n

RO Al

OR

OR

++ nROHRO

3-n

nO

R1

O

R2

R = CH2CH3 OPri R1= CH3 R2 = Ph

Figure 2 The synthesis of mixed alkoxy β-diketonato aluminium(III) complexes

from aluminium alkoxides41

Structures of Alkoxides

Alkoxide ions are the conjugate bases of alcohols and metal alkoxides are the

coordination compounds formed between metal ions and alkoxide ligands (fig 3i-iii)

As alcohols are only weak acids alkoxide ions are strong bases and metal alkoxides

tend to hydrolyze under condensation and elimination of alcohol when exposed to

water

1)

HO

2)

-O HOR -OR= =

3)

Mx(O Mx(OR)z=)z

Figure 3 i) Alcohol = hydrocarbon chain with a hydroxyl group ii) Alkoxide

Ion = deprotonated alcohol and iii) Metal alkoxide = coordination

compound with alkoxide ligands

Some possible hydrolysis and condensation reactions for metal with alkoxide ligands

are shown

M OR + H2O M OH + HOR

M OR + MHO M O + HORM

M OH + MHO M O +M H2O


6

According to Bradleyrsquos concept42

alkoxides have a strong tendency for

polymerization creating coordination polymers [M(OR)x]y (where y represents the

degree of polymerization) Degree of polymerization increases with the metal atomic

ratio Alkoxides take the smallest structural unit for the highest possible coordination

number of the metal Metal alkoxides [M(OR)x]y are well soluble in common organic

solvents and creates small oligomers with y = 2 3 or 442

Alkoxo RO- anion

possesses donor oxygen atom with three unpaired electrons which form covalent

bond with metal These anions might be coordinated to metal sites in terminal or

bridging way Alkoxides have physical properties that vary according to the nature of

the metal and alkoxy group They range from non-volatile insoluble solids to volatile

soluble solids This great variation in physical properties is due to the differing

molecular complexities observed in alkoxide chemistry those forming large

polymeric frameworks are insoluble and non-volatile while those forming small

oligomers are generally volatile and soluble

Alkoxides have a tendency to form oligomeric compounds [M(OR)x]y where RO-

groups are connected to two or even more metal sites This phenomenon affects the

reactivity and properties of these compounds The formation of oligomers or larger

polymeric frameworks is due to alkoxide groups bridging two or more metal centers

(ie acting as micro2 micro3 micro4 ligands) and the tendency of metals to increase their

coordination number The extent of oligomerization is affected by

(a) The Alkoxy Group For a given metal the more bulky the alkoxy group the lower

the degree of association

(b) The Metal The oxidation state of the metals determines the number of alkoxy

groups present per metal which in turn affects the bridging Low oxidation state

requires more bridges to achieve a given coordination number as compared to higher

oxidation state The size of the metal also play an important role to affect the degree

of bridging as larger the size of the metal atom more easily it can accommodate bulky

alkoxy groups and therefore more easily it can increase its coordination number

The versatile coordinating abilities of an alkoxo ligands leads to the formation of

structural pattern which range from simple bimetallic compounds to very complex

aggregates


7

R

O

M

R

O

M

R

O

M

O

R

MM

O

R

M M

O

R

M M

O

R

M M

O

R

MM

O

R

M MM

Figure 4 Coordination modes of an alkoxo ligand

Steric and electron demand of alkoxo groups have an influence on metal alkoxides

they form Electrophilic nature of metal cations allows attaching neutral ligands (eg

tetrahydrofuran pyridine etc) to the metal spheres Due to the saturating of metal

sites it is possible to obtain monomeric alkoxides [M(OR)xLy] (where L = neutral

ligand)

Alkoxides are highly versatile precursors for sol-gel synthesis4344

Alkoxides when

condensed form volatile alcohols andor ethers allowing for the formation of pure

products without impurities due to the precursor ligands In metal-organic chemical

vapour deposition (MOCVD) alkoxides are sometimes used as precursors4546

Examples of some of metal alkoxides having different structural features are depicted

below

TiOiPr

OiPr

PrOi

PrOi

= Ti(OiPr)4

Ti EtOEtO

EtO

EtO

EtO

OEt Ti

Ti

EtO OEt

OEt

EtO OEt

EtO Ti

OEt OEt

OEt

OEt

=Ti(OEt)16

Monomer47

Oligomer4849


8

Ce

PriO OiPr

PriO OiPr

PriO OPri

Ce

PriO OPri

OPriPriO

H

H

Alkoxide ndash alcohol adduct 50 51

Various so-called alkoxides are in fact oxo- or hydroxo-alkoxides which are the

condensation andor hydrolysis products of true alkoxides In oxo-alkoxides one or

more centrally placed bridging oxo ligands help to increase the coordination number

of the metal atoms The reactivity of oxo-alkoxides decreases with the ratio of

(bridging) oxo to alkoxo ligands Alkoxide derivatives may also contain other

ligands such as chloride ions or organic nonalkoxide ligands Chloro-alkoxides often

acquire structures similar to alkoxide structures but are normally avoided in sol-gel

synthesis as the chloride ions tend remain in the gel after hydrolysis as impurities in

the final materials

Ti

PriOPri

O

PriO

PriOO

OH

Ti

OPri

OPri

OPri

Ti

OPriPriO

=Ti3O(OH)(OiPr)9

Ti

PrOi PrOi

PrOi

PriO

PrOi

OiPr

Ti

OiPr

OiPr

OiPr

Y

ClCl

=YTi2(OiPr)9Cl2

oxo-hydroxo-alkoxide 52

chloro-alkoxide53

Apart from being versatile and important precursors in materials synthesis alkoxides

are also interesting from a structural point of view For example the choice of alkyl

group provides a means of systematic variation for the investigation of coordination

chemistry around metal and oxygen atoms The other parameters which can be

systematically varied are the number of oxo bridges and nuclearity

In the literature there are many examples of metal alkoxides it would be very

difficult to formulate a precise rule that could fully predict the final geometry of

forming alkoxide complex


9

Different structural pattern of metal alkoxides 54-69

Complex Structural pattern

[(C5H4CH3)4Y(micro-OCH=CH2)]2 Y2(micro-O)2 core

[Y3(micro3-OtBu)( micro3-Cl)( micro-O

tBu)3(O

tBu)4(thf)2 Y3(micro3-O)( micro-O)3O4 core

[Ti2(micro-OR)2(OR)4(acac)2]a (R=MeEt

iPr) [Ti2(micro-O)2O4 core

[Me4Zn4(micro3-OtBu)4 Zn4(micro3-O)4 core

[W2(OCMe2CMe2O)3] O3W= WO3 core

[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core

[Mg2V2(thffo)6Cl4]b Mg2V2(micro3-O)2(micro-O)4 core

[(thf)(OtBu)Y(micro-O

tBu)(micro-CH3)AlMe23] YAl3(micro-O)3O core

[Zr2Co2(micro3-OnPr)2(micro-O

nPr)4(O

nPr)4(acac)2]

a Zr2Co2(micro3-O)2(micro-O)4O4 core

[Al(OEt)2GaMe23] AlGa3(micro-O)6 core

[Nb2(micro-OMe)2(OMe)2(HOMe)2Cl4] Nb-Nb(micro-O)2O4 core

[Mo2(OiPr)4(HO

iPr)4 O4Mo=MoO4 core

[Pr3(micro3-tftb)2(micro-tftb)3(tftb)2]c Pr3(micro3-O)2(micro-O)3O4 core

[YNa8(micro9-Cl)( micro4-OtBu)( micro3-O

tBu)8(O

tBu)] YNa8(micro4-O)( micro3-O)8O core

[Na4Zr6(micro5-O)2( micro3-OEt)4(micro-OEt)14(OEt)6 Na4Zr6(micro5-O)2( micro3-O)4(micro-O)14O

core

[Ti7(micro4-O)( micro3-O)2(micro-OEt)8(OEt)12 Ti7(micro4-O)( micro3-O)2(micro-O)8O12 core aacac = acetylacetonato

bthffo=tetrahydrofuryloxo

ctftb= OCMe2(CF3)

In fact even minor changes in a ligand structure or reaction conditions can lead to the

geometry of the whole compound to be fundamentally different

Classification based on Alkoxide Complexes Structure

Metal alkoxide complexes can have very complex structures due to formation of

oligomeric and sometimes even polymeric aggregates Formation of alkoxy bridges

M-O(R)-M help the complexes to obtain maximal and preferred coordination even

though the number of bonded ligands per metal atom are too few Complexes are

categorized based on number of metal atoms in the complex Optimal coordination is

obtained by chelating ligand or by a shared (bridging) ligand atom

Mononuclear complexes ndash Mononuclear complexes are highly charged metal ions

where the coordination requirements are satisfied by the number of OR-ligands The

ligands are often large and branched with chelating abilities

Binuclear complexes - In binuclear complexes an oxygen atom in the ligand connect

the two metal atoms Usually at least two alkoxy bridges are connecting the metal

atoms and thus stabilizes the complex


10

Mo and W complexes can have metal-metal bonds to stabilize the complex (without

any bridging ligand) the multiplicity depends on the number and nature of ligands

Trinuclear complexes ndash These complexes are often triangular structures linear

chains or non-linear chains with the same type of connections as in the binuclear

complexes

Tetranuclear complexes ndash These complexes have several different types of

configuration The tetrahedral configuration has a core of μ4-O and four metal atoms

connected by the oxo-ligand but this is not a common configuration

Ti4(OR)

16 type is common and is built up by a M

4-rhomb with 2μ

3-O and 4μ-O The

R-groups are most often-primary alkyl groups for the 3d-metals

The cubane-like structure contains metal atoms in four opposite corners of a cube and

oxygen atoms in the other corners (4μ3-O)

Al4(μ4-O)(μ-OPr

i)5

complex70

and the [Eu4(OPri)10(HOPr

i)3]middot2HOPr

i

complex71

are

some of the examples without a metal-metal bond The Al4(OPr

i)12

type (the propeller


11

type) has an octahedron (with Al in the center) in the center and three tetrahedra of Al

connected by pairs of OR-bridges

A heterometallic example is the Nd[Al(OPr

i)4]

3 with the Nd atom in the center of the

complex72

Pentanuclear complexes ndash These complexes belong most often to either of two

different coordination

First the trigonal bipyramidand the square pyramid both with a μ

5-O in the center of

the M5O-cluster Second the structure with two triangles sharing a vertex Many

lanthanide oxo-isopropoxide complexes belong to the square pyramidal coordination

eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74

Hexanuclear complexes - Most common ones in hexanuclear complex are octahedral

M6-arrangement with a μ6-O in the center

or a structure with two M

3-triangles connected by the ligands the double propeller

type


12

Sol-Gel routes to metallic oxides

The goal is not only to obtain heterometallic alkoxides for fundamental studies but

should preferably be suitable for sol-gel processing and implementation in different

matrices The ligands plays important roles in the complexes changing the ligands

greatly affect their chemical behaviour and the way they act in sol-gel preparations

Sol-gel process is an efficient way of producing highly homogeneous pure

heterometallicoxides7576

with a well-controlled specific composition In Sol-gel

processes an alkoxide is first dissolved in a water-free organic solvent The precursor

solution can then be used to manufacture a great variety of different products such as

fine powders thin films fibers and ceramics depending on different manufacturing

steps as shown in Figure 5

Figure 5 Different steps in Sol-Gel process leading to different product

77-79

In the sol-gel synthesis two fundamental types of routes are possible (i) the metal-

organic (or organic) route and (ii) the inorganic route

The metal-organic route gives a better control over the process and is particularly

good when preparing high quality heterometallic oxides The inorganic route related

to ACG (Aqueous Chemical Growth) is much cheaper and easier to handle and is

often efficient for preparing highly crystalline oxides of specific shapes and size at

low temperatures but is not so useful for heterometallic oxides 75

The inorganic route

In the inorganic route metal salts such as acetates chlorides nitrates or sulphates are

dissolved in an aqueous solution and sol or precipitate is formed at a change of pH

temperature or concentration


13

Depending on the charge of the metal ion and the pH for the solution different

complexes such as aqua hydroxo and oxo complexes are formed

M (OH2)z+ M OH(z-1)+ + H+ M O(z-2)+ + 2H+ (Equ 1)

Figure 6 Metal ion charge (Z) vs pH 80

Figure 6 shows pH versus the metal ion charge (Z) areas typical of aqua hydroxo and

oxo ions The figure clearly shows that in acidic conditions M-OH2 complexes

observed for low-valence metal cations and in basic conditions M-O complexes are

observed for high-valence metal cations The area of the M-OH complexes is between

these areas Formation of a sol or precipitate occurs in the M-OH area

From the sol different condensation reactions can occur The condensation reactions

can be divided in two sub-categories olation where hydroxyl bridges are formed and

oxolation where oxo-bridges are formed 75

2M OH M (Equ 2)

(Equ 3)2M OH M + H2O

Olation

Oxolation

2(OH)

O M

M

Olation occurs for large metal ions with low charge Oxolation occurs very fast if the

metal ion is coordinatively unsaturated 75

The aqua-ligands are good leaving groups and poor nucleophiles while the oxo-

ligand has the opposite properties ie they have poor leaving groups and good


14

nucleophiles This means that no condensation can occur and no stable colloidal

solution can be obtained

The inorganic synthesis route is difficult to control for systems consisting of more

than one metal-ion due to the different properties of the metal-ions leading to different

pH ranges for precipitation Therefore there will be a preferential precipitation of one

metal-ion before the other in a multi-ion system On the other hand the inorganic sol-

gel route is a good choice for the monometallic systems when a desired shape and

phase can be produced at a low temperature and with cheap chemicals and

equipment7576

The metal-organic route

In metal-organic route metal-organic precursors mostly alkoxides are dissolved in

water-free organic solvents to form a homogeneous solution An alkoxide is a

derivative of an alcohol and consists of a metal or a semi-metal (M) an oxygen (O)

attached to an alkyl group (R) M-OR The starting chemicals for the synthesis and the

solvents must be carefully dried467576

as most of the alkoxides are extremely sensitive

to moisture and sometime also to oxygen

The first step in the metal-organic route is hydrolysis step where the alkoxo group is

changed for a hydroxo group while an alcohol molecule is expelled

M OR + H2O M OH + ROH (Equ 4)

In the next step the hydroxyl complexes M-OH react with another alkoxide or

hydrolyzed alkoxide molecule in one of two different ways olation or oxolation Both

these reactions are condensation reactions because metal-oxygen bridges are formed

while a small molecule is expelled The condensation phase can proceed as long as

sufficient water is available to form either a gel or a precipitate75

Olation

M OH M OHR M OH M+ + ROH

M OH M OH2 M OH M+ + H2O

(Equ5)

(Equ6)

Oxolation

M OH M OR M O M+ + ROH

M OH M OH M O M+ + H2O

(Equ7)

(Equ8)


15

A gel with specific desired structure and properties can be obtained by control of the

hydrolysis and condensation steps

Two fundamental types of gels can be formed particulate gels and polymeric gels

Particulate gels consist of spherical shape particles with dense or highly branched

polymers in size around a few nanometres to micrometres Polymeric gels on the

other hand have a low degree of branching of the polymer strands81

If the hydrolysis

and condensation reactions occur sequentially a polymeric gel is formed The

particular gel is formed when the hydrolysis is slow and the condensation reaction is

rapid Rapid hydrolysis and condensation reactions give colloidal gels or gelatinous

precipitates and low reaction rates result in a particle sols being formed75

General Synthetic Routes to Different Alkoxides

In alkoxides the metal is highly charged because of the low degree of electron

donation from the alkoxo oxygen to the metal75

The alkoxides are normally

polynuclear through sharing of alkoxo groups or oxo-oxygens and can be classified in

two groups homometallic alkoxides and heterometallic alkoxides All alkoxides are

with few exceptions (small p-block Si As P B S) very reactive to water Alkoxides

are very useful for producing hetero-metal oxides with exact composition and

ordering of the metals which is difficult to achieve with most techniques such as

CVD PVD and electrochemistry Homometallic alkoxides can be prepared in many

ways which to a great degree are dependent on the oxidation number of the metal ion

Hetero bi- or hetero polymetallic alkoxo complexes constitute an enormous family of

compounds with a very broad structural diversity Heterometallic alkoxides are

alkoxides containing two or more different kinds of metal-ions connected through

oxygenrsquos of the alkoxo-ligands

Synthetic Routes to Homometallic Alkoxides

The methods for synthesizing metal alkoxides are well established482

and the method

required for the synthesis of alkoxy derivatives of an element generally depends upon

its electronegativity Alkoxides can be prepared by several different synthetic

routes483-85

Some of the synthetic methods to produce desired metal Alkoxide are

described below


16

bull Reaction between metal and alcohol

M + n R-OH rarr M(OR)n + n2 H2 (g)

This method is limited to the most reactive metals such as alkaline metals alkaline

earth metals rare earth metals and aluminium Hydroxyl hydrogen gets replaced by

suitable metal cation with evolution of H2

bull Anodic oxidation of metal in alcohol

In this method due to the oxidation of metal at the anode cation and electron are

formed The electron and alcohol create hydrogen radical H and alkoxide anion

Molecular hydrogen exudes at the cathode

LiCl + R-CH2 -OH rarr Li-O-CH2 -R + frac12 H2 (g) + Cl

2 Cl + R-CH2 -OH rarr 2 HCl + R-CHO

The metal alkoxide produced by anodic oxidation is insoluble in the solvent and

therefore precipitates This method works for less reactive metals such as Zr Ta Nb

Co Fe and Ni An electro conductive additive (a halide) must often be added

The lithium chloride can react with the solvent alcohol and produces a lithium

alkoxide complex along with hydrogen and chlorine radical This radical reacts

further with the alcohol and produces hydrogen chloride and an aldehyde 86

bull Metal oxide or hydroxide reaction with alcohol

Metal hydroxides and oxides react with alcohols forming alkoxides and water

M-O + 2R-OH M-(OR)2 + H2O

M-OH + R-OH M-OR + H2O

Due to the reversible nature of these reactions it is necessary to remove water from

the reaction system Alkoxides of Mg Ca or Al are often used for obtaining water-

free alcohol since their reactions with water are irreversible

bull Reaction of Metal Halides with alcohol

MXn + n R-OH rarr M(OR)n + n HX

(X = H alkyl CequivC equivN NH2 NR2 SH N(SiR3)2 hellip)

Here the reaction between alcohol and metal halide leads to the substitution of halide

anion into RO- group forming appropriate metal alkoxide The hydrogen in the

alcohol interacts with the produced anion (from eg the metal hydride) and HX is

produced along with the metal alkoxide


17

bull Metathesis between two different metal complexes

MXn + n MOR rarr M(OR)n + n MX X=halide

This is the most common method for synthesis of metal alkoxides The solvent is

usually an alcohol mixed with another organic solvent used to decrease the solubility

of MX One disadvantage of this method is the formation of bimetallic complexes

However this can be avoided if ammonia is used instead of alkaline alkoxides

bull Alcohol exchange or transesterfication

One of the characteristic properties of metal alkoxides is their activity in the

substitution reactions of alkoxo groups

M(OR)n

+ nR-OH rarr M(OR)n + nR-OH

M(OR)n + nRCOOR rarr M(OR)n + nRCOOR

The alcohol produced in this reaction can normally be distilled off or the new metal

alkoxide can be precipitated to enhance the yield A drawback is that it can be

difficult to exchange all of the alkoxy groups in the complex leaving a mixed ligand

complex

Synthetic Routes to Heterometallic Alkoxides

Heterometallic complexes are of interest not only because of their attractive structural

chemistry catalytic properties and potential for industrial applications but also

because they constitute a group of molecular precursors for various metal oxide

materials In heterometallic alkoxide- or aryloxide- based complexes two or more

different metals might be held together by alkoxo or aryloxo bridging ligands

Coordinated alkoxo or aryloxo groups and alcohol or phenol molecules both attach to

the metal center resulting in excellent anchors for organometallic compounds

Heterometallic oxides have a wide range of applications in electronics optics

magnetism catalysis biomedical and environmental issues The methods described

above are the present ways to produce homometallic alkoxides Producing

heterometallic alkoxides ie alkoxides containing two different metal atoms requires

different approaches


18

Reaction between two alkoxide complexes

M(OR)n + qM(OR)m rarr MMq (OR)n+qm

This route is effective in the cases where one of complex is an alkaline metal or

alkaline earth metal alkoxide and the other is an alkoxide of a transition metal

preferably multivalent87

Reaction between a metal halide and an alkaline metal alkoxide

MXn + nMM(OR)m rarr MMn (OR)nm

+ nMX (s)

This route is used when one metal alkoxide is difficult to access whereas the halide

complex can be easily produced83

Synthetic Routes to Heterobimetallic Complexes

The formation of heterobimetallic complexes can occur due to one of the following

reactions

bull Alkoxide Routes

Mixed-metal species MMprime(OR)x+y generation depends on the difference in the

electronegativity between different metals ieM and Mprime insaturation stereolability of

alkoxides or oxoalkoxides of metal alkoxides M(OR)x Such reactions can be sensitive

to solvent presence of impurities such as water oxygen parent alcohol and method of

purification of alkoxides etc88

yM(OR)n + M(OR)n MMY(OR)n (OR)ny

Mostly studied heterometallic alkoxides are of the type MMprime(OR)6 where M = Li Na

K and Mprime = Nb Ta

The nature of the OR ligand can modify the stoichiometry between the metals as

shown in the following Ba-Zr system89

2Ba(OPri)2+ Zr4Ba2(OPri)20 4PriOH+2Zr2(OPri)(PriOH)2

Zr(OBut)2 Ba(OBut)2+ 12[ZrBa(OBut)6]2

Triphenylbismuth reacts with salicylic acid and the metal alkoxides

Ti(OCH(CH3)2)4 and M(OCH2CH3)5 (M = Nb Ta) to produce the heterobimetallic

complexes Bi2M2(sal)4(Hsal)4(OR)4


19

Figure 7 Bi2M2(sal)4(Hsal)4(OR)4

By the Reaction of Alkoxides with Metal β-diketonates

An interesting way to the preparation of heterometallic complexes is the reaction

between a metal alkoxides and β-diketonate complex of another metal atom The Ba-

Ti and Sr-Ti examples demonstrate that a convenient set of ligands can stabilize

mixed-metal β-diketonato alkoxides and even tune their MMprime stoichiometry Some

examples of these are as BaTi2(thd)4(OEt)8(EtOH)2 where thd =(ButCOCHOCO

But)90

formed by reacting titanium ethoxide and barium tetra methyl heptanedionate

in 11 stoichiometry Reaction of titanium isopropoxide with strontium tetra methyl

heptanedionate gave Sr2Ti2(η2-thd)4(μ3-OPri)2(μ-OPr

i)4(OPr

i)2 having rhombus

structure (Figure 8)91

Figure 8 Molecular structure of Sr2Ti2(η2-thd)4(μ3-OPri)2(μ-OPr

i)4 (OPr

i)2

bull By the Reaction of Alkoxides with Metal Carboxylates

The solubility of metal acetates in organic solvents is very low but can be improved

in the presence of metal alkoxides by the formation of heterobimetallic species For

example anhydrous metal acetates M(OAc)2 (M = Mg Pb Cd) are solubilized in


20

hydrocarbons in the presence of niobium alkoxides at room temperature giving

trimetallic species Nb2M(μ-OAc)2(OR)10

M(OAc)2 + [Nb(OR)5]2

HexaneNb2M(OAc)2(OR)10

room temp

Where M = Mg Pb Cd and R = Pr Et

bull Salt Elimination Reactions

Heterobimetallic complexes are also synthesized by substitution of all halide ligands

in a metal halide by anionic alkoxo- metallates

MCln + uMMy(OR)2 M[My(OR)2]n + nMCl

ZnCl2 + Ti2Sn(OEt)6 ZnSn(OEt)6 + 2TiCl4

Metal halides (MCln) are of three categories ie (i) divalent and trivalent transition

metals such as Cr Mn Fe Co Ni Cu etc (ii) lanthanides and actinides (iii) Pb(II)

Sb(III)

bull Condensation Reactions

In Condensation reactions the elimination of small molecules such as ether alcohol

water carboxylic acid or ester as volatile by-product takes place For example

heterobimetallic oxoalkoxide bridges can be obtained according to the following

chemical reactions

M(OR)n + M(OL)n (RO)n-1M-O-M(OL)n-1 + ROL

Where L = CH3COO- group and RʹOL is a volatile by-product

Sometimes heating could be required for the dissolution of some metal acetates and

condensation takes place with the elimination of ester92

The condensation of metal

(II) acetate with alkoxides leads to the product of type (RO)nM-O-M(II)-O-M(OR)n

where M = Al(II) Ti(IV) M(II) = Mg Cr Mn Fe Co Zn Mo Pb

For the last two decades evolutionary studies have been carried out for the synthesis

and characterization of polymetallic clusters and cages93-98

as these compounds have

proved importance in developments of several fields of bioinorganic chemistry99-104

magnetochemistry105-107

solid-state physics108-114

and material science

Almost all transition metals throughout the periodic table form metal compounds

utilizing different kinds of bridging organic and inorganic ligands93-96115116

The


21

involvement of carboxylato oxo and alkoxo bridges provide interesting exchange

coupling in various cases In this sense alkoxo-aliphatic ligands or simply the

aminoalcohol ligands can be expected to improve the coupling between two or more

metal centers forming homo or heteronuclear complexes374546117118

Homoleptic Alkoxides

A great number of homoleptic Cu- and Zn-alkoxides with simple aliphatic or aromatic

alkoxide ligands (eg OMe OEt OiPr O

tBu OCEt3 OCH2CH2NMe2 OCH2CH2O

Me and OAr) are known119-127

Homoleptic heterometallic alkoxides suitable as precursors for materials such as

M[Al(OR)4]2 [ClMndashZr2(OPri)9]2 or M[Zr2(OPr

i)9]2 (M=Cu Zn) are available via salt

metathesis eg by KCl elimination or reaction of anionic nucleophilic Al or Zr-

alkoxide complexes with MCl2 89128

Synthetic Routes to Heteroleptic Alkoxides

Alkoxide complexes with two or more different ligands known as heteroleptic

alkoxides and can be prepared by chemical modifications A metal alkoxide reacts

with an acidic organic ligand or by reaction of the metal alkoxide with a β-diketonate

(eg acetylacetone (Hacac H3C-C(O)-CH2-C(OH)-CH3) or a carboxylate metal

complex

M(OR)n + mHZ rarr M(OR)n-m Zm

+ mROH

Z=acidic organic ligand

Complexes with a β-diketonate or a carboxylate ligand are less reactive to hydrolysis

as compared to ordinary alkoxide complex due to larger negative charge on the

carboxylate or β-diketonate ligand and a chelating effect

The reaction with a β-diketonate complex is another way to prepare heterometallic

alkoxides but it may also result in heterometallic heteroleptic alkoxides For

heterometallic complexes the solvent should be purely hydrocarbon based such as

toluene or hexane129-131

If alcohol is added it behaves as a Lewis base and formation

of heterometallic complex would be interrupted and a ligand exchange reaction could

occur instead132

Properties and Reactivity of Metal Alkoxides

In metal alkoxides M-OR the organic moiety R attached to oxygen may be alkyl

substituted alkyl chelating alkyl or alkenyl and has a substantial influence on the

structure and properties of the metal alkoxides The steric effect of the R group has a


22

controlling influence on the volatility of the metal alkoxides82

Thus the alkoxides

with less bulky alkyl groups eg methyl and ethyl proved to be oligomers (eg

dimers trimers and tetramers) due to the bridging property of the alkyl group which

may be bonded through its oxygen to two or three metals through μ2 or μ3 fashion

respectively by means of conventional two-electron covalent bonds 133134

Bond lengths vary in the order M-OR terminal lt M-μ2-OR lt M-μ3-OR These

structures are retained in non-polar organic media Polynuclear species can also be

obtained via an oxo ligand and the elements with large metallic radii having small

valency such as divalent (Ba Sr) and trivalent (In Ln Fe Al) and this favour the

stability of oxo-derivatives rather than alkoxides oligomers and their alcohol solvated

analogs135136

The oxo ligand is an versatile ligand which can be linked to more

metals around 2minus6 than an OR ligand and thus increase the metal coordination

number in the absence of a neutral ligand L137138

Metal alkoxides M(OR)n are very reactive towards wide variety of molecules having

acidic protons which helps in chemical modifications of organic hydroxyl derivatives

such as alcohols silanols R3SiOH glycols OH(CH2)nOH carboxylic and hydroxyl

carboxylic acids hydroxyl surfactants etc to achieve tuneable properties

1m[M(OR)n]m + aXH 1m[M(OR)n-aXa]m + aROH

X= RCO2 β-dik

Hydrolysis

Metal alkoxides are rapidly hydrolyzed leading to the formation of hydroxides or

hydrated oxides

2Al(OR)3 + 6H2O Al2O33H2O + 6ROH

or 2Al(OH)3

This means that during handling such materials great care must be taken to exclude

moisture However if a restricted amount of water is used then this may lead to

formation of oxyalkoxides

2Ti(OBut)4 + H2O (OBut)3Ti-O-Ti(OBut)3 + 2ButOH

When a restricted amount of water is added partial hydrolysis occurs sometimes-

yielding products of definite composition known as oxide alkoxides

2Al(OR)3 + 2H2O Al2O(OR)4 + 2ROH


23

2Al(OR)3 + 2H2O Al2O2(OR)2 + 4ROH or Al2(OH)2(OR)4

Reaction with Alcohols

Functionalized alcohols at room temperature easily interchange alcoholic groups in

the metal alkoxides while heating is required for complete exchange by classical

alcohols These are known as alcoholysis reactions which increase the solubility of

metal alkoxides The reaction can be represented by the following general equation

M(OR)m + xROH M(OR)m-n(OR)n + xROH

These reactions appear to proceed through the SN2 type mechanism involving a four-

centered cyclic transition state

O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on

Figure 9 Mechanism of the reaction

Functionalized alkoxide ligands such as O(CH2)nX [X = OR (alkoxyalcohols) NR2

(aminoalcohols)] with intermolecular O or N donor sites can be bridging or chelating

(Figure 10) Chelation generally requires formation of a cycle which takes place by

bonding the alkoxides oxygen and the donor site X to the metal The size of the ring

depends upon the value of lsquonrsquo in the (CH2)n eg the value n = 2 is for 2-

methoxyethanol and it forms five membered rings in complexes

Group replacement by functional alcohols has also been found to solubilize some

insoluble alkoxides as polymeric metal alkoxides of some metals such as Ni Cu Sn

etc It usually depends upon their ability to act as a chelating ligand rather than a

bridging one and in this respect aminoalcohols are often more efficient than

alkoxyalcohols This behaviour is shown by polymeric Cu(II) alkoxides [Cu(OR)2]infin

(R = Me Pri Bu

t) in which alcohol exchange reactions afford insoluble copper(II) 2-

methoxyethoxide [Cu(OC2H4OMe)2]2 whereas Cu(OC2H4NMe2)2 is a monomer

volatile and soluble139

Similar is the case with the soluble Ba(teaH2)2 2EtOH and


24

[Cu(teaH2)]43teaH3 species which are obtained by alcoholysis of insoluble methoxide

by triethanolamine N(C2H4OH)3(teaH3) and volatility can be enhanced by steric

effects such as substitution in the α-position a strategy used for forced chelation140

The different modes of coordination of functionalized alcohols in monoanionic

alkoxides (x = OR NR2 and M is atom of same or different elements) are as follows

O

M

X

O

M M

X

Terminal or pendant ƞ1

Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2

Bridging-chelating micro2-ƞ2

Figure10 Different modes of coordination of functionalized alcohols

Reaction with β-diketones

Metal alkoxides reacts readily with chelating β-diketones because of the availability

of number of M-OR bonds for hydrolysis Titanium isopropoxide [Ti(OPri)4] is highly

reactive towards air and moisture due to unsaturated four coordinate Ti(IV) The

moisture sensitivity of the Ti based precursors can be reduced by the insertion of

chelating β-diketone groups to increase the coordinative saturation of the Ti(IV)


25

center to make Ti(OPri)2(acac)2

141 Similarly [Zr(OPr

i)3(thd)]2 the symmetric dimer is

the most stable complex which has significant advantages over Zr(OPri)4 and Zr(thd)4

due to its high volatility and stability142

Thermal stability of the Ta(OEt)4(dbm)

complex is due to delocalization of the negative charge into an extended conjugated

electron system involving the orbitals of the phenyl groups in the dibenzoylmethanate

ligand143

Reaction with Carboxylic Acid

The reactivity of metal alkoxides with carboxylic acids is rather complex as compared

to β-diketones as the competitive reactions can occur The three different situations

are as follows

Substitution

M(OR)n-x(RCO2)x 12[(OR)n-x-1M-O-M(RCO2)x-1] + RCO2R

Generation of oxo ligands by either non-hydrolytic condensation or elimination of an

ester from an unstable carboxylatoalkoxide


Hydrolysis which leads to esterification

ROH + RCO2H RCO2R + H2O

This depends on the experimental conditions as stoichiometry acidM(OR)n tempera-

ture nature of the acid solvent and duration The increase in temperature causes an

increase in the number of oxo ligands Polynuclear complexes of titanium alkoxides

such as Ti6O4(μ-OBu)4(OBu)4(μ-OAc)8144

is obtained at room temperature while

heating drives the reaction towards more oxo species Ti6O6(OEt)6(μ-O2CR)6145146

Reactions wih Hydrogen halides Halogens and Acyl halides

Metal halides are used as the starting materials for the synthesis of metal alkoxides

However the alkoxides can be converted to metal halides or mixed alkoxy-halides by

reaction with halogen hydrogen halide or acyl halide


26

i) xHX + M(OR)n M(OR)n-x(X)x + xROH

ii) X2 + M(OCH2R)nMX2(OCH2R)n-2 + 2RCH2O

RCH2OH + RCHO

iii) xRCOX M(OR)n M(OR)n-xXx + RCOOR+

Reactions with Organic Esters and Silyl Esters

Metal alkoxides react with organic esters to form new alkoxy derivatives

i) M(OR)n + xCH3COOR M(OR)n-x(OR)x + xCH3COOR

ii) M(OR)n + xR3SiOH M(OSiR3)n-x(OR)x + xROH

Reactions with Glycols

Glycols are di-hydroxy alcohols and react readily with metal alkoxides to form

glycolates(chelated or bridged) or mixed alkoxide glycolates Due to presence of a

large organic chain glycolates tend to form highly polymeric derivatives compared to

the analogous alkoxide derivatives and are more resistant to hydrolysis Mixed

glycolates can be obtained by reactions of monoalkoxide monoglycolates with

different glycols in equimolar ratios

M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH

Reactions with Schiff Bases and β-ketoamines

General mode of reaction of Metal alkoxides with Schiff bases and β-ketoamines is as

shown below

i) M(OR)n + x(HO)RC=NR (RO)n-xM(O(R)C=NR)x + xROH

ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27

Reactions with Oximes and Hydroxylamines

The reaction of metal alkoxides with oximes and Hydroxylamines provides many

different routes for synthesis of variety of derivatives of Boron aluminium tin

titanium silicon etc

i) M(OR)n + xR2C=NOH M(OR)n-x(ON=CR2)x + xROH

ii) M(OR)n + xR2C=NOH M(OR)n-x(ON=CR2)x + xROH

Meerwein-Ponndorf-Verley Reaction

Metal alkoxides catalyzed the reduction of ketones by alcohols of which aluminium

alkoxides are the best The reaction completes by the removal of the volatile ketone

formed

Me2HC-OH + R2C=O Me2C=O + RHC-OH

Thermal Decomposition of Alkoxides

Metal alkoxides decompose on heating to the metal oxides hydroxides or to the metal

itself with the evolution of organic species The mode of decomposition depends not

only on the alkoxide but on the conditions of the pyrolysis

Uses of Alkoxides

Alkoxides are moisture-sensitive and require special handling techniques but this

property does not restrict their uses in various fields They have many industrial

applications A brief summary of some of these is given below

Catalysts

The alkoxides are used as catalysts in the Meerwein-Ponndorf-Verley reaction and in

ring opening polymerizations However there are other systems catalysed by

alkoxides Ziegler-Natta polymerisations147

trans esterifications148-151

and polyester

formation152-154

Polymer Cross-Linking Agents

Many alkoxides have the ability of to promote cross-linking which makes them useful

in a variety of ways For example titanium and zirconium alkoxides may be used in

films where rapid drying is required155

while aluminium titanium and zirconium

alkoxides may be used in conjunction with silicones in the waterproofing of leather

where it is believed that the alkoxides promote the curing of the silicone156


28

Precursors to Metal Oxides (Glasses and Ceramics)

Metal alkoxides are very susceptibility to hydrolysis This property has led to a major

use of alkoxides the formation of high purity metal oxides by the pyrolysis of the

hydroxides formed on the controlled hydrolysis of alkoxides157

The metal alkoxides

are readily purified by distillation under reduced pressure or by recrystallisation so the

oxides produced are free from impurity

Heterometallic Oxo-alkoxides

Preparation by ester elimination reactions

This method has general applicability for synthesis of heterobimetallicalkoxidesof a

number of metals158

and even of organometallic moieties159

as illustrated by the

following equations

M(OAc)2 + Al(OPri)3

Xylene

RefluxM(OAc)OAl(OPri)2 + 2PriOAc

The solvent like pyridine play the role of a coordination leading to ligand exchange

rather than ester elimination reactions between Sn(OBut)4 and Sn(OAc)4 Me3Si(OAc)

In hydrocarbon solvents (eg toluene) contrary to the ester elimination reaction

occurring generally in such systems158-162

formation of an addition product Nb2Cd(micro-

OAc)2(micro OPri)4(micro OPr

i)6has been reported

163 from Nb(OPr

i)5 and Cd(OAc)2

Cd(OAc)2 + 2Nb(OPri)5 CdNb2(OAc)2(OPri)10

Condensation Reactions between oxo- and normal metal alkoxides

The commonly utilized route for bimetallic alkoxides synthesis heterometallic oxo-

alkoxides is synthesis by the condensation of component alkoxides and oxo-alkoxide

In view of the importance of Y-Ba precursors for 123 superconductors a novel

barium yttrium oxo-alkoxide [Y4Ba2(micro6-O)( micro3-OEt)(dpm)6] has been synthesized164

by the following reaction

[Y4Ba2(micro6-O)( micro3-OEt)(dpm)6]Y5O(OPri)13 + Ba + PriOH + EtOH

(dpm= ButC(O)CHC(O)Bu

t)

Reactions between Metal Halides and Alkali Alkoxo- metallates

This type of reaction which has been utilised extensively for synthesis of

heterometallic normal alkoxides has been reported for heterometaloxo-alkoxides The

reaction between SmI and NaTi(OPrl) yields165

[Sm4Ti(micro5-O)(micro3-OPri)2(micro-

OPri)6(OPr

i)6] which could also be isolated by the reaction between Sm5O(OPr

i)3 and

Ti(OPri)4


29

Similarly the reaction at room temperature between ZnI2 and KTa(OPri)6 (12

stoichiometry) yields ZnTa202(OPri)8

166 Another interesting micro-oxo-centered iron

heterometal methoxide derivative Na2Fe6O(OMe)186MeOH has been synthesized by

the reaction between iron(III) chloride and sodium methoxide

Na2Fe6O(OMe) 186MeOH+ 6MeOH + Me2O6FeCl3 + 20 NaOMe

Other Methods for Synthesis of Heterometallic oxoalkoxide Derivatives

In addition to the condensation of a metal oxo-alkoxide with the alkoxide of another

metal the interaction of normal alkoxides of two metals also under some conditions

yields a heterometaloxo-alkoxide eg

Fe(acac)3 + 3Zr(OPrn)4Zr3Fe(O)(OPrn)10(acac)3

Decomposition method

At high temperatures volatile thermolysis products of alkoxides can contain alcohols

ethers aldehydes saturated and unsaturated hydrocarbons etc The structures of

crystalline products provide evidence for condensation attendant on this process

Copper oxosilane oxide [Cu18O2(OSiMe3)14] was prepared by vacuum distillation of

CuOSiMe3 Evidently the process is accompanied by destruction followed by

condensation of the resulting fragments Decomposition of W4(OPri)10 to

[WIII

4O2(OPri)8]2 occurs with elimination of propane

167 Thermolysis of bimetallic

isopropoxides Sb(OPri)4 afforded crystalline [K2Sb2O(OPr

i)6]2 and Pr

i2O Refluxing

of toluene solutions of KMIII

(OBut)4 (M

III=Sb Bi) over a long period of time resulted

in elimination of isobutylene and afforded the oxo complexes [K4MIII

2O(OBut)8] It

should be noted that Na-containing compounds with the same composition are

generated already in the step of the reaction of NaOBut with M

III(OBu

t)3

168

If decomposition of alkoxides occurs at rather low temperatures the reaction gives

ethers as the major products For instance thermolysis of methoxides Al(OMe)3

Pb(OMe)2 and NaAl(OMe)4 (at ~120 oC) afforded dimethyl ether as the only gaseous

product169- 171

Heating of an alcoholic solution of Ti(OEt)4 in an autoclave at 100 oC

led to crystallisation of Ti16O16(OEt)32 and elimination of Et2O172 173

Condensation with elimination of ethers proved to be one of the main pathways of

spontaneous decomposition of alkoxides

M-OR + RO-M M-O-M + R2O


30

The formation of oxo bridges is undoubtedly thermodynamically favourable and in

the case under consideration is analogous to ageing of oxide hydrates accompanied

by condensation of two hydroxy groups with elimination of a water molecule This

type of reaction174

was used for the preparation of oxo compounds by

transesterification of niobium ethoxide with tert-butyl alcohol

Nb(OEt)5 + ButOH Nb(OBut)3 + Nb2O(OBut)8 + But2O + EtOH

The proposed mechanism involves the heterolytic cleavage of the O-R bond followed

by the attack of the resulting carbocation on the M-O bond of another OR group

Ethers (like other volatile decomposition products for example unsaturated

hydrocarbons) are not always detectable against the background of alcohols175

Decomposition of bimetallic alkoxides to oxoalkoxometallates MmMrsquonOp(OR)q

containing heterometallic M-O-Mrsquo bridges is of most importance among the reactions

under consideration

Sn(OR)4 + Cd(OAc)2 Cd4Sn4O2(OR)10(OAc)10 + AcOR

R=CH2But

Since such complexes readily eliminate ester they were proposed as precursors in the

synthesis of complex oxides from the gaseous phase (CVD method)

Applications of Mixed-Metal oxides


magnetism catalysis biomedical and environmental issues Some important

examples are mentioned here

Lead titanate (PbTiO3) has pyroelectric and piezoelectric properties due to its

ferroelectric nature This is used in pyro-detectors and acoustic transducers

In capacitors and sensors Barium titanate (BaTiO3) is used as it is dielectric

material

(LiNbO3Ti) has electro-optic properties and is used in second harmonic

generation wave-guide devices and optical modulators

[K (TaNb)O3] is also a pyroelectric electro-optic material and has applications in

pyrodetectors wave guide devices and frequency doublers130

In semiconductor devices Magnesia aluminate (MgAl2O4) used as coating on

silicon


31

Yttrium-barium-copper oxide (YBa2Cu3O7) a high temperature super conductor

has some commercial applications176

Lead zirconate titanate [Pb(ZrTi)O3 PZT] and lead lanthanum zirconate

titanate [(PbLa)(ZrTi)O3 PLZT] have many applications They are used in

pyrodetectors non-volatile memory surface acoustic wave devices wave-guide

devices optical memory display due to their dielectric pyroelectric piezoelectric

and electro optic properties130

Ba2Cu3O5+x and CuO have been employed as catalysts for CO oxidation one of

the most important reactions in air pollution control processes177178

Nickel-cobalt catalyst is useful for hydrogen or synthesis gas production through

the partial oxidation of methane179

Cu and ZnO-based catalysts are used for large-scale industrial synthesis of

methanol from COCO2H2180

New high-temperature superconductors eg REBa2Cu3O7 (where RE = rare

earth) play a key role in various technological applications181

Among the common oxide precursors such as metal β -diketonates M(β-dik)n

carboxylates and alkoxides the latter are the most versatile for customizing properties

at a molecular level and conversion into extended arrays31581

Rational design of

precursors and optimization of the ligand requires a knowledge of the relationships

between the properties of the materials and of their precursors130149

which should thus

be structurally well defined

Metal β-diketonates

β-diketonate chelating system with six membered metal containing ring is the most

commonly used ligand in the coordination chemistry182183

(A B C = CR where R = H Alk Ar Het n = oxidation state of metal)184


32

β-diketonates have coordination capabilities along with the formation of chelates

(intra complex compounds) The possible modes of O- and O O

- coordination in

mono di and polynuclear β-diketonates shown in following structures (Figure 11)

β-Diketonates have been used as chelating ligands for almost 120 years184

Metal β-

diketonates [M (RCOCHCORprime)n]m are mostly used in material science due to their

high volatility They are mostly monomeric due to chelating behaviour of the ligand

but association take place for divalent and large elements such as alkaline earth

metals185

In Cancer treatment especially β-diketonate complexes of titanium antitumor agents

are a promising replacement for the platinum heavy metal complex cisplatin186187

β-

Diketonate supported metal-alkoxide aryloxide and halogenate complexes are easily

synthesized from available commercial metal precursors utilizing reliable and

reproducible syntheses which are important considerations from an industrial view

point

Here (R1 R2 R3) = H alkyl aryl (M M

1 M

2) = different metal atoms and m =

oxidation state of metal

Figure 11 Some O- and O O

- coordination modes of β-diketonates

The β-diketones or 1 3-diketones bear two carbonyl groups that are separated by one

carbon atom This carbon atom is the α-carbon In most β-diketones the substituents

on the α- carbon are hydrogen atoms The substituent on the carbonyl function can be

an alkyl group a fluorinated alkyl group an aromatic or a heteroaromatic group The

parent and most common 1 3-diketone is acetylacetone (Hacac) which is prepared by

the reaction of acetone and acetic anhydride with the addition of BF3 catalyst (Figure

12) were the substituents on both carbonyl groups are methyl groups

Various different β-diketones can be considered as derived from acetylacetone by

substitution of the CH3 groups by other groups and therefore they are well-known


33

chelating ligands mostly available commercially at relatively low cost Examples of

other common β-diketones are benzoylacetone (Hbzac) benzoyltrifluoroacetone

(Hbtfac) dibenzoylmethane (Hdbm) hexafluoroacetylacetone (Hhfac) 2-thenoyl

trifluoroacetone (Htta) 2266-tetramethyl-35-heptanedione (Hthd) and 6677888-

heptafluoro-22-dimethyl-35-octanedione (Hfod)

O

+O

O O OH O

Figure12 Preparation of acetylacetone

Exchange of ligand is a common method to coordinate β-diketonate ligands to the

metal center resulting in the formation of complexes with many transition metals

where both oxygen atoms bind to the metal

β-diketonates undergo keto-enol tautomerism 188

(Figure 13) These tautomers are in

equilibrium with each other and structurally they show a cis configuration (enol) and

a syn (cisoid) conformation (keto)

O O

R R

O OH

RR

O OH

RR

Keto form enol forms

Figure 13 keto-enol tautomerism

The amount of keto and enol form can be determined by integration of the keto and

the enol resonance peaks in the 1H NMR spectrum The position of the ketondashenol

equilibrium depends on a various factors such as the substituents on the β-dicarbonyl

system the solvent the temperature and the presence of other species in solution that

are capable of forming hydrogen bonds The presence of an alkyl substituent on the α-

carbon decreases the amount of enol form Bulky alkyl groups such as the isopropyl

group or the sec-butyl group reduces the amount of enol form to almost 0The

presence of a methyl group in the α-position depresses the amount of enol form in

other β-diketones than acetylacetone For example presence of a methyl group in the

α-position of benzoylacetone reduces the amount of enol form from 98 in pure


34

benzoylacetone to 4 in the methyl-substituted benzoylacetone During

deprotonation of the β-diketone the proton is removed from the α-carbon (if the β-

diketone is in the keto form) or from the alcohol group (if the β-diketone is in the enol

form) β-diketone acidity depends on the substituents Electron-withdrawing groups

increase the acidity whereas electron-donating groups decrease it Because of the

presence of the two carbonyl groups the proton on the α-carbon is quite acidic and

relatively weak bases can remove it Ammonia sodium hydroxide piperidine and

pyridine are some examples of bases that are used for deprotonation of β-diketones

are A much stronger base is required for removing second proton

The enolic hydrogen atom of the β-diketonate can be replaced by a metal cation to

give a six-membered chelate ring shifting the keto-enol equilibrium towards the

enolate form (Figure 14)189

O O

RR

M

Figure 14 Six-membered chelate ring

β-Diketonate chelates are synthesized by the reaction of ligand with metal salts in

water organic solvents or in solvent mixture β-Diketonate ligand replaces the

ligands of metal salts For example

TiCl4 + 4K(ligand) Ti(ligand)4 + 4KCl

The direct syntheses of metal β-diketonates may be carried out from a number of

starting reagents ie M MOx M(CO3)x MHx Metal alkoxides will undergo

exchange reactions in a simple stoichiometric ratio This synthetic route has

advantages over direct methods in the sense of isolation of very pure materials if

enough care is taken in the preparation of the starting metal oxides (ie the use of

anhydrous oxygen free solvents and rigorous handling techniques) 190

Ti(OPri)4 + n(-dik)Hexane

[Ti(OPri)4-n(-dik)n]x + nHOPri

Metal β-diketonate complexes are attractive and extensively used precursors in oxide

MOCVD due to their high volatility The volatility of β-diketonate complexes be

increased by increasing the steric bulk of the R group


35

Structure of Titanium β-Diketonates

Over the fifty years reaction between a tetraalkoxy titanium and β-diketones has been

known The initial studies191192

failed to isolate pure compounds or to provide

convincing analytical data Yamamoto and Kambara 193

in 1957 on basis of IR

spectroscopy and cryoscopy first isolated and predicted structures of titanium β-

diketonate complexes for the ethoxide and n-propoxide derivatives (Figure 15) They

described the octahedral coordination around the titanium metal centers

O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5

R = C2H5 n-C3H7-C4H8

Figure 15 Structures (proposed) by Yamamoto and Kambara (11 and 12 ratio)

Mehrotra and co-workers153-155

later prepared the chloro and a wider range of alkoxy

derivatives However it remained unclear whether the complexes had cis-substituted

or trans-substituted structures with respect to the metal center In separate studies

Bradley194

and Fay195196

rejected the possibility of the trans configuration in favour of

cis based on variable temperature 1H NMR and IR spectroscopy studies They

observed a splitting of the acetyl acetonate (acac) methyl proton resonance into a

doublet at low temperatures for several homologous titanium compounds

Ti(acac)2(OR)2 which they explained as having a cis configuration where the two

methyls have magnetically inequivalent positions (eg Figure 16 where R = Rrsquo = Me)

In 1993 Keppler and co-workers197

proposed that solution NMR data and crystal

structures of known bis(BDK) titanium(IV) complexes (BDK = β-diketonate)

indicates that an equilibrium mixture of three cis isomers in solution is obtained as

shown below

M

O

O

XO

XO

R

R

R

R

cis-cis-cis(C1) cis-cis-trans(C2) cis-trans-cis(C2)

M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R

Figure 16 Isomers in solution for cis-[Ti(BDK)2X2]


36

Thus it is believed that the cis configurations are more strained as compared to trans

But still cis preferred by electronic effects due to the significance of π-bonding (pπ

oxygen rarr dπ metal) 197198

as all three d orbitals of titanium would participate in the

cis complex whereas only two d orbitals would be involved in the trans complex

Furthermore β-diketonates are bonded more efficiently to the metal center than the X

groups (usually oxo alkoxo aryloxo or halogenato ligands) and therefore they are

the trans-directing group

In monomeric structures of titanium β-diketonate complexes significant distortion

from the ideal octahedral geometry indicates that the distances between titanium

metal and the oxygen atoms in β-diketonate chelates of titanium (IV) are usually not

symmetrical For example the cis-[Ti(BDK)2(OR)2] complexes show relatively short

Ti-OR bonds (18 Aring) and longer TiO(BDK) bonds with Ti-O distances trans to OR

distinctly longer than the bonds cis to OR (206 vs 200 Aring) 199

In the reaction of titanium alkoxides with β-diketonates due to a preferred

coordination number of six for titanium188

the third or fourth alkoxy groups are not

replaced and bis- β-diketonate derivatives were always obtained even if excess of

these chelating ligands was used

The first crystal structure of a mixed acetylacetonearyloxide complex of titanium

(Figure17) was synthesised by Bird and co-workers200

who observed that the

phenoxide ligands were in a cis position same was observed for mixed acetyl-

acetonealkoxide complexes

Figure17 Molecular structure of C34H48O6Tin-bis-(24-pentanedionato)

bis(26diisopropylphenoxo)titanium(IV)200

Brown et al201

in 2005 published two more mixed β-diketonatearyloxide complexes

of titanium using BINOL(11-Bi-2-naphthol) as the aryloxide ligand and

dibenzoylmethane(DBM) and (DMHD) Dimethyl-heptandionate They studied the


37

electronic dissymmetry of these compounds by DFT calculations and showed that a

chiral electronic structure can exist even in a symmetrical fragment such as

bis(diketonate)titanium(IV)

Serpone et al202

in 1972 first resolved monosubstituted compounds [Ti(BDK)(Hal)3]

The compound was surprisingly a μ2-Cl bridged dimer as shown in Figure 18

Figure18 Structure of [Ti(acac)Cl3]2

Schiff bases

Schiff base was first reported by Hugo Schiff in 1864203

Schiff base metal complexes

have been studied extensively because of their attractive chemical and physical

properties and their wide range of applications in numerous scientific areas Ligand a

metal surrounded by a cluster of ions or molecule is used for the preparation of the

complex compounds named as Schiff base which are condensation product of

primary amine and aldehyde or ketone The speciality of Schiff base is that many

kinds of amine can be chosen to react with aldehyde or ketone to get the ligand with

different structures as well as some variable properties

The findings of structural studies are interesting in that the Schiff base ligands can

control the stereochemistry of the complex and provide us with numerous examples of

unusual geometries about the central metal ion Therefore they can serve to illustrate

the coordination flexibility of these ions

Schiff bases play an important role as ligands in metal coordination chemistry even

after almost a century since their discovery Modern chemists still prepare Schiff

bases and nowadays active and well-designed Schiff base ligands are considered as

ldquoprivileged ligandsrdquo Schiff bases are important class of ligands due to their synthetic


38

flexibility their selectivity and sensitivity towards the central metal atom structural

similarities with natural biological substances and also due to the presence of the

imine group (N=Clt) which imparts in elucidating the mechanism of transformation

and rasemination reaction in biological system

Schiff bases can be prepared by condensing carbonyl compounds and amines in

different conditions and in different solvents with the elimination of water molecules

A Schiff base is a nitrogen analog of an aldehyde or ketone in which the C=O group is

replaced by C=N-R group It is formed by condensation of an aldehyde or ketone with

a primary amine according to the following scheme

R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base

The common structural feature of these compounds is the azomethine group with a

general formula RHC=N-R where R may be alkyl aryl cyclo alkyl or heterocyclic

groups which may be variously substituted

Schiff bases that contain aryl substituents are substantially more stable and more

readily synthesized as compared to those which contain alkyl substituents Schiff

bases of aliphatic aldehydes are relatively unstable and readily polymerizable while

those of aromatic aldehydes having effective conjugation are more stable

The formation of a Schiff base from an aldehydes or ketones is a reversible reaction

and generally takes place under acid or base catalysis or upon heating

R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39

The formation generally moves to the completion by separation of the product or

removal of water or both By aqueous acid or base many Schiff bases can be

hydrolyzed back to their aldehydes or ketones and amines

The presence of a dehydrating agent normally favours the formation of Schiff bases

Though the Schiff bases are stable solids care should be taken in the purification

steps as it undergoes degradation Excellent chelating ability and considerable

chemical importance of Schiff bases is due to presence of a lone pair of electrons in

sp2 hybridised orbital of nitrogen atom of the azomethine group Examples of a few

compounds are given in Figure 19 This chelating ability of the Schiff bases combined

with the ease of preparation and flexibility in varying the chemical environment about

the C=N group makes it an interesting ligand in coordination chemistry

NN

HH

NH HN

NH2N

H

HN

NN-bis(pyrrole-2-carboxalidene)-12-diaminobenzene

N-pyrrole-2-carboxalidene-12-diaminobenzene

NHS

H

HO

NH2N

H

HO

N-salicylidene-2-aminothiophenol N-salicylidene-12-diaminobenzene

NH2

NN NHO

H

HO

N-salicylidene-2-aminophenolN-pyridine-2-carboxalidene-11-binaphthyl-22-diamine

Figure 19 Some examples of Schiff bases


40

Treating metal salts with Schiff base ligands under suitable experimental conditions

generally prepare metal complexes of the Schiff bases However for some catalytic

application the Schiff base metal complexes are prepared in situ in the reaction

system Cozzi204

in his review has outlined five synthetic routes that are commonly

used for the preparation of Schiff base metal complexes and are depicted as shown

below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2

Figure 20 Preparation of Schiff base complexes

The use of metal alkoxides (M(OR)n) is shown in method 1 Alkoxides of early

transition metals (M = Ti Zr) are commercially available and easy to handle In the

case of highly moisture-sensitive derivatives of lanthanides the use of other alkoxide

derivatives is not easy Metal amides M(NMe2)4 (M = Ti Zr) are also employed as the

precursors in the preparation of Schiff base metal complexes (method 2) The reaction

occurs via the elimination of the acidic phenolic proton of the Schiff bases through the

formation of volatile NHMe2

Other synthetic routes include reaction of metal alkyl complexes with Schiff bases

(method 3) or reaction of the Schiff base with the corresponding metal acetate under

reflux conditions (method 4) The synthetic scheme presented in method 5 consists of

a two-step reaction involving the deprotonation of the Schiff bases followed by

reaction with metal halides


41

SCOPE OF THE PRESENT INVESTIGATIONS

Literature review has revealed that there has been ever growing interest in the field of

metal alkoxides and their derivatives with different types of ligands and their

application in various fields Hence it was considered worthwhile to synthesize some

new heterometallic micro-oxo compounds and carry out their reactions with different

ligands such as β-diketones Salicylates Cycloalcohols and Schiff bases in order to

get an insight its structural features The compounds and there derivatives have been

synthesized and characterized on the basis of elemental analysis infrared 1H NMR

13C NMR and Mass spectral studies

The work in the thesis has been broadly classified into the following sections

1 Synthesis of Heterotrimetallic [Al(III)Sn(II)Ti(IV)]-micro-oxo-iso propoxide micro-oxo

n-propoxide [SnO2TiAl(OPri)2(OPr

n)3] and its derivatives

β-diketone derivatives of heterotrimetallic [Al(III)Sn(II)Ti(IV)]-micro-oxo-

isopropoxide micro-oxo n-propoxide [SnO2TiAl(OPri)2(OPr

n)3]

Schiff bases derivatives of heterotrimetallic [Al(III)Sn(II)Ti(IV)]-micro-oxo-


n)3]

Cycloalcoholic derivatives of heterotrimetallic [Al(III)Sn(II) Ti(IV)]-micro-oxo-


n)3]

2 Synthesis of Heterotrimetallic dibutyl [Al(III)Sn(IV)Ti(IV)]-micro-oxo-isopropoxide

micro-oxo n-propoxide [Bu2SnO2TiAl(OPri)2 (OPr


β-diketone derivatives of heterotrimetallic dibutyl [Al(III)Sn(IV)Ti(IV)]-micro-

oxo-isopropoxide micro-oxo n-propoxide [Bu2SnO2TiAl(OPri)2(OPr

n)3]

Schiff base derivatives of heterotrimetallic dibutyl [Al(III) Sn(IV) Ti(IV)]-micro-

oxo-isopropoxide micro-oxo n-propoxide [Bu2SnO2TiAl(OPri)2(OPr

n)3]

Salicylate derivatives of heterotrimetallic dibutyl [Al(III)Sn(IV) Ti(IV)]-micro-


n)3]


2

involving other inorganic salts These features make the metal oxides derived from

metal alkoxides highly pure with specific properties like high hardness chemical and

mechanical resistance and high temperature stability The softndashchemical approach is

a flexible simple and novel synthesis for industrial production Different types of

precursor can lead to change in unique features of the structural framework that

affects the physical and chemical properties in the final product by retaining the

stoichiometric ratio under control This will help to predict favorable morphology for

its futuristic applications with high reliability accuracy and reproducible results5-14

From above mention feature it is evident that metal alkoxides play the key role for

preparing materials of excellent functions and shapes

A range of catalytic applications of Group (IV) (ieTi Zrand Hf) is mainly due to the

Lewis acidic nature of M(IV) complexes Group (IV) elements are important

components of electro ceramics such as lead zirconium titanate (PZT) and barium

titanate Sol-gel processing of these and related materials is based upon hydrolysis of

alkoxide solutions It is found that the species produced when acetylacetone (acacH)

is added to Ti(OR)4 is 11 reaction product [Ti(OR)3(acac)] which is dimeric readily

under-go ligand redistribution in solution to give Ti(OR)4 and [Ti(OR)2(acac)2] 17

O

NMR spectroscopy has been used to investigate the hydrolysis of the resulting

mixture for R = Pri and the results were interpreted in terms of the hydrolysis behavior

of the individual mononuclear components Titanium complexes of alkoxide and

aryloxide ligands exhibit a rich coordination chemistry and reactivity and find

applications in various fields15

The interest in the development of non-metallocene

complexes for the polymerization of α-olefins16

has created a new range of chelating

dialkoxo17-24

ligands for group IV transition metals Complex formation may be

effected by the steric bulk on the ligands Furthermore the olefin polymerization

reactivity by a possible catalyst may strongly depend on the crowding around the

metal as substantial bulk on one hand may hinder the approach of an incoming

olefin and on the other hand decelerate termination processes25-28

Several types of

amine bis (phenolate) titanium complexes having different steric crowding around

the metal have been synthesized The [ONNO]-type ligands bind to the metal in a

tetradentate fashion leads to octahedral bis-(isopropoxide) complexes regardless of

the steric bulk of the aromatic ring substituents Various complexes involving

ethylenediamine and metal alkoxides with particular reference to complexes involving


3
















genation30






















Aqueous




4








R1

O

R2

NH4

e-3(NH

4)2SO

4H2OCH

3OH

Al

O

O

R1

R2

3

3O

R1

O

R2

Method II AlCl3 +

3O

R1

O

R2


(freshly prepared)

-3 HCl(g)

-3 H 2O(g)

EtOH


complexes














(Figure 2)3441








5



AlH

O

O

R1

R2

n

RO Al

OR

OR

++ nROHRO

3-n

nO

R1

O

R2









water

1)

HO

2)

-O HOR -OR= =

3)

Mx(O Mx(OR)z=)z





are shown





6








Alkoxo RO- anion

























aggregates


7

R

O

M

R

O

M

R

O

M

O

R

MM

O

R

M M

O

R

M M

O

R

M M

O

R

MM

O

R

M MM






ligand)


Alkoxides when





below

TiOiPr

OiPr

PrOi

PrOi

= Ti(OiPr)4

Ti EtOEtO

EtO

EtO

EtO

OEt Ti

Ti

EtO OEt

OEt

EtO OEt

EtO Ti

OEt OEt

OEt

OEt

=Ti(OEt)16

Monomer47

Oligomer4849


8

Ce

PriO OiPr

PriO OiPr

PriO OPri

Ce

PriO OPri

OPriPriO

H

H










the final materials

Ti

PriOPri

O

PriO

PriOO

OH

Ti

OPri

OPri

OPri

Ti

OPriPriO

=Ti3O(OH)(OiPr)9

Ti

PrOi PrOi

PrOi

PriO

PrOi

OiPr

Ti

OiPr

OiPr

OiPr

Y

ClCl

=YTi2(OiPr)9Cl2


chloro-alkoxide53










9





tBu)3(O






[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core





nPr)4(O

nPr)4(acac)2]




[Mo2(OiPr)4(HO




tBu)8(O



core



ctftb= OCMe2(CF3)

















10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


3
















genation30






















Aqueous




4








R1

O

R2

NH4

e-3(NH

4)2SO

4H2OCH

3OH

Al

O

O

R1

R2

3

3O

R1

O

R2

Method II AlCl3 +

3O

R1

O

R2


(freshly prepared)

-3 HCl(g)

-3 H 2O(g)

EtOH


complexes














(Figure 2)3441








5



AlH

O

O

R1

R2

n

RO Al

OR

OR

++ nROHRO

3-n

nO

R1

O

R2









water

1)

HO

2)

-O HOR -OR= =

3)

Mx(O Mx(OR)z=)z





are shown





6








Alkoxo RO- anion

























aggregates


7

R

O

M

R

O

M

R

O

M

O

R

MM

O

R

M M

O

R

M M

O

R

M M

O

R

MM

O

R

M MM






ligand)


Alkoxides when





below

TiOiPr

OiPr

PrOi

PrOi

= Ti(OiPr)4

Ti EtOEtO

EtO

EtO

EtO

OEt Ti

Ti

EtO OEt

OEt

EtO OEt

EtO Ti

OEt OEt

OEt

OEt

=Ti(OEt)16

Monomer47

Oligomer4849


8

Ce

PriO OiPr

PriO OiPr

PriO OPri

Ce

PriO OPri

OPriPriO

H

H










the final materials

Ti

PriOPri

O

PriO

PriOO

OH

Ti

OPri

OPri

OPri

Ti

OPriPriO

=Ti3O(OH)(OiPr)9

Ti

PrOi PrOi

PrOi

PriO

PrOi

OiPr

Ti

OiPr

OiPr

OiPr

Y

ClCl

=YTi2(OiPr)9Cl2


chloro-alkoxide53










9





tBu)3(O






[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core





nPr)4(O

nPr)4(acac)2]




[Mo2(OiPr)4(HO




tBu)8(O



core



ctftb= OCMe2(CF3)

















10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


4








R1

O

R2

NH4

e-3(NH

4)2SO

4H2OCH

3OH

Al

O

O

R1

R2

3

3O

R1

O

R2

Method II AlCl3 +

3O

R1

O

R2


(freshly prepared)

-3 HCl(g)

-3 H 2O(g)

EtOH


complexes














(Figure 2)3441








5



AlH

O

O

R1

R2

n

RO Al

OR

OR

++ nROHRO

3-n

nO

R1

O

R2









water

1)

HO

2)

-O HOR -OR= =

3)

Mx(O Mx(OR)z=)z





are shown





6








Alkoxo RO- anion

























aggregates


7

R

O

M

R

O

M

R

O

M

O

R

MM

O

R

M M

O

R

M M

O

R

M M

O

R

MM

O

R

M MM






ligand)


Alkoxides when





below

TiOiPr

OiPr

PrOi

PrOi

= Ti(OiPr)4

Ti EtOEtO

EtO

EtO

EtO

OEt Ti

Ti

EtO OEt

OEt

EtO OEt

EtO Ti

OEt OEt

OEt

OEt

=Ti(OEt)16

Monomer47

Oligomer4849


8

Ce

PriO OiPr

PriO OiPr

PriO OPri

Ce

PriO OPri

OPriPriO

H

H










the final materials

Ti

PriOPri

O

PriO

PriOO

OH

Ti

OPri

OPri

OPri

Ti

OPriPriO

=Ti3O(OH)(OiPr)9

Ti

PrOi PrOi

PrOi

PriO

PrOi

OiPr

Ti

OiPr

OiPr

OiPr

Y

ClCl

=YTi2(OiPr)9Cl2


chloro-alkoxide53










9





tBu)3(O






[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core





nPr)4(O

nPr)4(acac)2]




[Mo2(OiPr)4(HO




tBu)8(O



core



ctftb= OCMe2(CF3)

















10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


5



AlH

O

O

R1

R2

n

RO Al

OR

OR

++ nROHRO

3-n

nO

R1

O

R2









water

1)

HO

2)

-O HOR -OR= =

3)

Mx(O Mx(OR)z=)z





are shown





6








Alkoxo RO- anion

























aggregates


7

R

O

M

R

O

M

R

O

M

O

R

MM

O

R

M M

O

R

M M

O

R

M M

O

R

MM

O

R

M MM






ligand)


Alkoxides when





below

TiOiPr

OiPr

PrOi

PrOi

= Ti(OiPr)4

Ti EtOEtO

EtO

EtO

EtO

OEt Ti

Ti

EtO OEt

OEt

EtO OEt

EtO Ti

OEt OEt

OEt

OEt

=Ti(OEt)16

Monomer47

Oligomer4849


8

Ce

PriO OiPr

PriO OiPr

PriO OPri

Ce

PriO OPri

OPriPriO

H

H










the final materials

Ti

PriOPri

O

PriO

PriOO

OH

Ti

OPri

OPri

OPri

Ti

OPriPriO

=Ti3O(OH)(OiPr)9

Ti

PrOi PrOi

PrOi

PriO

PrOi

OiPr

Ti

OiPr

OiPr

OiPr

Y

ClCl

=YTi2(OiPr)9Cl2


chloro-alkoxide53










9





tBu)3(O






[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core





nPr)4(O

nPr)4(acac)2]




[Mo2(OiPr)4(HO




tBu)8(O



core



ctftb= OCMe2(CF3)

















10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


6








Alkoxo RO- anion

























aggregates


7

R

O

M

R

O

M

R

O

M

O

R

MM

O

R

M M

O

R

M M

O

R

M M

O

R

MM

O

R

M MM






ligand)


Alkoxides when





below

TiOiPr

OiPr

PrOi

PrOi

= Ti(OiPr)4

Ti EtOEtO

EtO

EtO

EtO

OEt Ti

Ti

EtO OEt

OEt

EtO OEt

EtO Ti

OEt OEt

OEt

OEt

=Ti(OEt)16

Monomer47

Oligomer4849


8

Ce

PriO OiPr

PriO OiPr

PriO OPri

Ce

PriO OPri

OPriPriO

H

H










the final materials

Ti

PriOPri

O

PriO

PriOO

OH

Ti

OPri

OPri

OPri

Ti

OPriPriO

=Ti3O(OH)(OiPr)9

Ti

PrOi PrOi

PrOi

PriO

PrOi

OiPr

Ti

OiPr

OiPr

OiPr

Y

ClCl

=YTi2(OiPr)9Cl2


chloro-alkoxide53










9





tBu)3(O






[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core





nPr)4(O

nPr)4(acac)2]




[Mo2(OiPr)4(HO




tBu)8(O



core



ctftb= OCMe2(CF3)

















10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


7

R

O

M

R

O

M

R

O

M

O

R

MM

O

R

M M

O

R

M M

O

R

M M

O

R

MM

O

R

M MM






ligand)


Alkoxides when





below

TiOiPr

OiPr

PrOi

PrOi

= Ti(OiPr)4

Ti EtOEtO

EtO

EtO

EtO

OEt Ti

Ti

EtO OEt

OEt

EtO OEt

EtO Ti

OEt OEt

OEt

OEt

=Ti(OEt)16

Monomer47

Oligomer4849


8

Ce

PriO OiPr

PriO OiPr

PriO OPri

Ce

PriO OPri

OPriPriO

H

H










the final materials

Ti

PriOPri

O

PriO

PriOO

OH

Ti

OPri

OPri

OPri

Ti

OPriPriO

=Ti3O(OH)(OiPr)9

Ti

PrOi PrOi

PrOi

PriO

PrOi

OiPr

Ti

OiPr

OiPr

OiPr

Y

ClCl

=YTi2(OiPr)9Cl2


chloro-alkoxide53










9





tBu)3(O






[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core





nPr)4(O

nPr)4(acac)2]




[Mo2(OiPr)4(HO




tBu)8(O



core



ctftb= OCMe2(CF3)

















10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


8

Ce

PriO OiPr

PriO OiPr

PriO OPri

Ce

PriO OPri

OPriPriO

H

H










the final materials

Ti

PriOPri

O

PriO

PriOO

OH

Ti

OPri

OPri

OPri

Ti

OPriPriO

=Ti3O(OH)(OiPr)9

Ti

PrOi PrOi

PrOi

PriO

PrOi

OiPr

Ti

OiPr

OiPr

OiPr

Y

ClCl

=YTi2(OiPr)9Cl2


chloro-alkoxide53










9





tBu)3(O






[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core





nPr)4(O

nPr)4(acac)2]




[Mo2(OiPr)4(HO




tBu)8(O



core



ctftb= OCMe2(CF3)

















10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


9





tBu)3(O






[Ga2(micro-OtBu)2

tBu4] Ga2(micro-O)2

core





nPr)4(O

nPr)4(acac)2]




[Mo2(OiPr)4(HO




tBu)8(O



core



ctftb= OCMe2(CF3)

















10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


10





complexes




Ti4(OR)


4-rhomb with 2μ

3-O and 4μ-O The




Al4(μ4-O)(μ-OPr

i)5

complex70


i)3]middot2HOPr

i

complex71

are


i)12

type (the propeller


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


11




i)4]


complex72







eg the [Eu4III

EuIIO(OPr

i)12

(HOPri)] HOPr

i complex

73 and Ln5O(OPr

i)13 Ln = Nd

Gd or Er74





type


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


12














77-79








The inorganic route





13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


13













2M OH M (Equ 2)


Olation

Oxolation

2(OH)

O M

M






14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


14









equipment7576

















Olation



(Equ5)

(Equ6)

Oxolation



(Equ7)

(Equ8)


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


15







If the hydrolysis






















and the method



routes483-85


described below


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


16

































17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


17










M(OR)n






complex















18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


18








+ nMX (s)





reactions


















19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


19








But)90




i)4(OPr

i)2 having rhombus



i)4 (OPr

i)2






20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


20





room temp









Sb(III)





chemical reactions

















The


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


21




















complex


+ mROH











occur instead132






22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


22


Thus the alkoxides










analogs135136









X= RCO2 β-dik

Hydrolysis


hydrated oxides


or 2Al(OH)3









23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


23










O

H

RM

RO

ROOR

ORO

R

HM

RO

ROOR

OR

(+ROH)

M

RO

ROOR

OR

(+ROH)

and so on













(R = Me Pri Bu






24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


24






O

M

X

O

M M

X


Bridging micro2-ƞ1

X

MO

X

MO

M

Chelating ƞ2










25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


25









ligand143




are as follows

Substitution


















26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


26



RCH2OH + RCHO













M(OR)x + n HO

HO

(RO)x-2n M

O

O

+ 2nROH



shown below


ii) M(OR)n + x NR

HOR

HOR

(RO)n-x (M

OR

OR

NR)x

+ 2nROH


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


27










formed






Uses of Alkoxides




Catalysts





and polyester

formation152-154









28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


28





The metal alkoxides






number of metals158



following equations

M(OAc)2 + Al(OPri)3

Xylene









163 from Nb(OPr

i)5 and Cd(OAc)2










t)






OPri)6(OPr


i)3 and

Ti(OPri)4


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


29



















[WIII




i)6]2 and Pr

i2O Refluxing


(OBut)4 (M



2O(OBut)8] It



III(OBu

t)3

168




product169- 171







30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


30




type of reaction174










under consideration


R=CH2But










material






silicon


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


31



















Rational design of



which should thus







32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


32



- coordination in



Metal β-




metals185



β-




point


1 M















33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


33






O

+O

O O OH O









O O

R R

O OH

RR

O OH

RR














34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


34













O O

RR

M


















35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


35










O

O

H3C

R

Ti(OR)3

O

O

H3C

R

Ti

OR

OR

O

O

R

CH3

R = CH3OC2H5







Bradley194

and Fay195196











shown below

M

O

O

XO

XO

R

R

R

R


M

O

O

XO

XO

R

R

R

R

M

O

O

XO

XO

R

R

R

R



36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


36



























Brown et al201





37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


37




Serpone et al202




Schiff bases



















38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


38










R NH2

Primary amine

R C R

O

Aldehyde or ketone

+ C + H2O

R

R

N R

Schiff base










R C R

O

+ R NH2

R C

OH

NHR

R

Aldehydeor ketone

Primaryamine

Carbinolamine

R C R

NR

+ H2O

N-substituted imine

Water


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


39












NN

HH

NH HN

NH2N

H

HN



NHS

H

HO

NH2N

H

HO


NH2

NN NHO

H

HO




40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


40




system Cozzi204



below

R1

R1

OYN

N

R2

R2 OY

R1

R1

1) Y=H M(OR)n

2) Y=H M(NR2)n

3) Y=H MRn

4) Y=H M(OAc)n

5) Y=NaK MXn

R=AlkylAryl

X=ClBr

R1

R1

ON

N

R2

R2 O

R1

R1

M Xn-2















41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]


41
















n)3]



n)3]



n)3]






n)3]



n)3]



n)3]

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