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STUDIES ON METAL CHELATESOF

SOME SCHIFF’S BASES

A THESIS SUBMITTED TO THE

SAURASHTRA UNIVERSITY FOR THE DEGREE OF

Doctor of Philosophy

IN

THE FACULTY OF SCIENCE (CHEMISTRY)

BY

Mr. ARVINDKUMAR M. VIRPARIA

UNDER THE GUIDANCE

OF

Dr. P. K. Patel

CHEMISTRY DEPARTMENT MAHARAJA SHREE MAHENDRASINHJI SCIENCECOLLEGE,

MORBI- 363 642 GUJARAT (INDIA)

2013

The Sarvodaya Education Society’s

Maharaja Shree Mahendrasinhji Science College Nazar Baugh, Bhadiyad Road, Morbi-363 642.

Dr. P. K. Patel Residence: M.Sc., Ph.D. ‘Aum’ Principal, 4-Avani Park Society, Maharaja Shree Opp. P.G. Clock, Mahendrasinhji Science College, Shanala Road, Morbi - 363 642 Morbi - 363 641 Phone(O): - 02822-240601 Phone(R)02822224755

Statement under O. Ph. D. 7 of Saurashtra University

The work included in the thesis is my own work under the supervision of Dr. P. K. Patel and leads to some contribution in chemistry subsidized by a number of references.

Dt.: - 01 - 2013 (Arvindkumar M. Virparia)

Place: Morbi

This is to certify that the present work submitted for the Ph.D. Degree of Saurashtra University by Arvindkumar M. Virparia is his own work and leads to advancement in the knowledge of chemistry. The thesis has been prepared under my supervision.

Date : - 01 - 2013 Dr. P. K. Patel

Place : Morbi Principal` MaharajaShree

Mahendrasinhji Science College Morbi - 363 642

Dedicated

To my

Beloved family

And

My

“Guruji”

ACKNOWLEDGEMENTS

“Shree Ganeshay Namah”

It is a moment of gratification and pride to look back with a sense of contentment at the long traveled path, to be able to recapture some of the fine moments, to be think of the infinite number of people, some who were with me from the beginning, some who joined me at different stages during this journey, whose kindness, love and blessings has brought me to this day. I wish to thank each of them from the bottom of my heart.

First and foremost, I wish to pay my homage and devote my emotions to “Lord Ganesha”, “The Wonderful Chemist” of this lovely world without whose blessings this task would not have been accomplished. I bow my head in utter humility and complete dedication.

I bow my head with absolute respect and pleasantly convey my heartily thankfulness to my co-traveler and my research guide, most respectable Dr. Praful K. Patel, who continued to support my aspiration with lots of love and encouragement. I consider myself privileged to work under his generous guidance, because I got the newer creative dimensions and positive attitude in my thinking and analyzing capacity, which helped me to make things simple but programmatic. I am always indebted to him. He constantly encouraged me to remain focused on achieving my goals. His observations and comments helped me to establish the overall direction of the research and also move forward expeditiously with investigation in depth.

I would like to extend my deepest sense of indebtness to shri Chhabilbhai Sanghavi, Hon. President, and all members of SES for their support, encouragement and facilities provided by them to use Maharaja Shre Mahendrasinhji Science College Laboratory.

Above all, I bow my head with utter respect to my beloved parents late Vajiben and Mohanbhai for this accomplishment of my life. Also I can never forget my brithers Valjibhai, Govindbhai and Manshukhbhai.

I do not hence any word to express my gratefulness to my wife Gita and children Tanmay and Utsav who stood beside me during my work. Their love and smiling face boosted up me.

I wish to Special thanks to Dr. J. M. Parmar, Dr. D. R. Bhadja, Dr. B. M. Bheshdadia, Dr. M. V. Parsania, and Dr. B. M. Sharma, DR. V.A Modhvadiya, Dr.K.M.Rajkotia Dr. H. C. Mandavia, Mr. H. O. Jethva, Dr. J. G. Raiyani, Mr. N. H. Manani, Dr. R. R. Ranjan, Dr. N. S. Panchal, Mr. S. S. Babariya, Mr. V. M. Katba, Mr. R.D. Kalaria, Mr. D. M. Sanghani, Mr. B. M. Patel, and for them constant guidance and moral support whenever I needed during the course of my research work.

I would like to express my deep sense of gratitude and lots of love towards my dearest friends Dr. A. J. Rojivadiya, Dr. D. O. Odedara, Mr. H.H. Ranavaia, Dr. A. H. Bapodara, Dr. J. J. Upadhya, and Dr. J. J. Modha, Mr. L. M. Vagela, Dr. D. M. Purohit Dr. D. S. Kundariya,

I also like to thanks to Mahendra, Pravin, Haresh, Dilip, Dharmendra,Dilip kalaria, dinesh, Bharat, Rakesh, Govind Dr.kantaria, Prakashbhai, Haresh Charola, Sureshbhai Marvania, I am really very much thankful to God for giving me such nice friends.

I also owe to, Dr. P. H. Parsania, Professor and Head Department of Chemistry, Saurashtra University, Rajkot. DR. D. K. Raval, Dr. N. J. Parmar

I would also like to thank teaching and non-teaching staff members of M. M. Science College, Morbi for their kind help and moral support during course of my research work.

I wish to Special thanks to My Adhytmic Guruji H.H. Shri Shivkrupand Swamiji and Pujya Guruma

I gratefully acknowledge the most willing help and co-operation shown by CDRI Lucknow and SAIF Punjab University, Chandigarh, Chemistry Department Saurashtra University Rajkot for spectral studies and Chemistry Department S. P. University V. V. Nagar for providing Magnetic Analysis. And Sicart, V.V. Nagar for providing thermal analysis

Finally, I express my grateful acknowledgment to Department of Chemistry, M. M. Science College, Morbi, for providing me the excellent laboratory facilities and kind furtherance for accomplishing this work

Mr.Arvindkumar M.Virparia

CONTENTS

Page. No.

SYNOPSIS 1 CHAPTER - 1

Introduction and literature survey on Schiff bases and their

Metal Chelates. 6

Reference 23

CHAPTER - 2

Experimental: Synthesis of Schiff base and their Metal Chelates. 29

Reference 40

CHAPTER - 3

Analytical and spectral study of Schiff base and their Metal Chelates. 41

Reference 94

CHAPTER - 4

Thermal Analysis of Metal Chelates. 95

Reference 107

CHAPTER - 5

Magnetic Measurement. 109

Reference 133

CHAPTER - 6

A comprehensive summary of work 135

Reference 152

Studies on metal chelates……………….. Synopsis

1

STUDIES ON METAL CHELATES OF SOME SCHIFF’S BASES

Hugo Schiff described the condensation between an aldehyde and an

amine leading to a Schiff base in 1864 1. Schiff base ligands are able to

coordinate metals through imine nitrogen and another group, usually linked to

the aldehyde. The coordination chemistry of Schiff bases has attracted the

attention of several investigators 2-5. Nitrogen, oxygen and /or sulphur-

containing ligands and there metal complex have been found to possess

significant biological and pharmacological activities and are used as catalyst,

fungicides, bactericides, tuberculostatic and anticarcinogenic agents 6. Schiff

bases have been used as corrosion inhibitors 7.

The coordination complexes have found extensive application in

various fields of human interest. These including extraction, dyeing, water

softening etc. These metal complexes containing ligands play an important

role as catalyst in many bioinorganic systems. Many chelating ligands find

extensive applications as reagent and masking agents in various titrimetric,

spectrophotometric, chromatographic methods. Thus complexation studies of

Schiff bases are particular attention by coordination chemists.

1. Schiff H. Ann. Suppl. 1864; 3; 343.

2. Patel MN, Patel KM, Patel NH, Patel KN. Synth. React. Inorg.Met.-

Org.Chem.2000;30:1965

3. Cukurovali A, Yilmaz I, Ozmen H, Ahmedzade M. Trans. Met.

Chem.2002; 27: 171

4. Khan MMT, Halligudi SB, Shukla S, Shark J. Jou. Mol. Catal. 1990; 57:

301.

5. Bhattacharya PK. Chem. Sci. 1990; 102: 247.

6. Singh MS, Singh AK, Tawada K. Synth. React. Inorg.Met.-

Org.Chem.2002; 32: 639.

7. Achouri M, Kertit S, Salem M, Essassi EM, and Tellal M; Bull. Of

Electrochem., 1998; 14: 462.


2

The work presented in the thesis with title "STUDIES ON

METAL CHELATES OF SOME SCHIFF’S BASES” has been

described into six chapters:

CHAPTER- 1 Introduction and literature survey on Schiff bases

and their Metal Chelates.

CHAPTER- 2 Experimental: Synthesis of Schiff base and their

Metal Chelates.

CHAPTER- 3 Analytical and spectral study of Schiff base and

their Metal Chelates.

CHAPTER- 4 Thermal Analysis of Metal Chelates.

CHAPTER- 5 Magnetic Measurements.

CHAPTER- 6 A comprehensive summary of work

CHAPTER- 1 INTRODUCTION

This chapter of the thesis describes the general introduction, Schiff

base, Importance of Schiff bases, uses of coordination compounds, Literature

survey, Present work, and Reference.

CHAPTER- 2 EXPERIMENTAL

2.1 Syntheses of Schiff bases

This section is deal with synthesis of amine and their Schiff bases.

• Synthesis of Amine 1, 1’ bis (4-aminophenyle) cyclohexane [ A ]

Compound [A] was prepared by condensation of cyclohexanone and

excess aniline as follow 8-9. To a solution of cyclohexanone 0.101 mole and

aniline 0.267 mol in 25 ml of 35% HCl at 110ºC for 17-18 h.(yield 51.48 % of

light – yellow crystal M.P.110-112 M.F.C18H22N2, F.W.=266GM)

8. Mi Hie YI, Wenxi Huang, Moon Young Jin, and Kil–Yeong Choi,

Macromolecules,1997, 30 (19),5606-5611.

9. Myska,J. Chem. Abstr.1964,61,14558.


3

Synthesis of Schiff base:

• 6,6’-(4,4’-(cyclohexane-1,1-diyl) bis(4,1-phenylene)) bis (azan-1-yl-1-

ylidene) bis (methan-1-yl-1-ylidene) bis (2-methoxy phenol) (L1-o-v-A)

and

• 2,2’-(4,4’-(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(azan-1-yl-1-

ylidene)bis(methan-1-yl-1-ylidene) diphenol (L2- sal-A)

• 1,1’-(4,4’-(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(azan-1-yl-1-

ylidene)bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol(L3-O-H-Naph.-A)

Synthesis of Schiff base by condensation of 50ml solution of 2-

hydroxyl -3- methoxy benzaldehyde (7.6gm , 50mmol.) in hot ethanol and

50ml solution of 1, 1’ bis ( 4-aminophenyle) cyclohexane (6.65gm,25mmol) in

hot ethanol. using glacial acetic acid as a catalyst and reaction mixture was

reflux on water bath for 4-5 h. a solid mass was separated out on cooling, it

was suction filtered, washed with sodium bisulfite solution, water and finally

with ethanol. Subsequently dried over anhydrous CaCl2 in desiccators. The

Schiff base are recrystallized from chloroform and purity was checked by TLC

in appropriate solvent system at room temperature The Same procedure was

adopted for the other ligands

N N CH

HO

O

HC

OH

O


4

2.2 Synthesis of Metal Chelates of Schiff base:

The metal chelates of the Schiff base were synthesized by mixing

(1:1mol) a chloroform-ethanolic (1:1, 30ml) of Schiff base, L1-O-V-A or L2-

Sal- A or L3-O-H-Naph.-A with an ethanolic solution (30 ml ) of metal solt or

metal acetate. The resulting mixture was refluxed with stirring on a magnetic

stirrer equipped with heater for 5-6 h. on cooling, the colored chelates

precipitated out, which was filtered by suction, washed several times with

ethanol and finally with ether, and dried over anhydrous CaCl2 .The metal ions

selected were Cu (II), Ni (II), Co (II) & Zn (II) proposed structure of metal

Chelates will be as following

N N CH

O

O

CH3

HC

O

O

CH3

M+2

CHAPTER – 3 Analytical and spectral study of Schiff bases and their

Metal chelates.

This chapter of thesis deals with the Elemental analysis, Conductivity

Measurements, Solubility, spectral characterization of Schiff base and their

metal chelates it gives functional groups ,quantitative structure of the

Compound.


5

CHAPTER – 4 Thermal Analysis of Metal Chelates:

This Chapter deals with determinations of change in chemical or

physical properties of material as a function of temperature in a controlled

atmosphere. Thermo gravimetric analysis (TGA), measured weight changed

in a material as a function of temperature. The TGA data provide important

experimental evidence in determining the number of water molecules present

in the metal chelates. It is best tool for understanding decomposition

mechanism etc.

CHAPTER – 5 Magnetic Measurements:

This chapter deal with Magnetic susceptibility Measurements on the

vibration sample magnetometer (VSM), model 7304, Lake Shore Cryotronics,

inc., U.S.A., was used to characterize magnetic prosperities of the metal

chelates. The effective Magnetic moment µeff was calculated from the

expression: µeff. = 2.84 (χ m X T) 1/2, where T = absolute temperature (K)

CHAPTER – 6 A comprehensive summary of work

This chapter of the thesis describes a comprehensive summary of the

work incorporated in the thesis.

Studies on metal chelates……………….. Chapter-1

6

General Transition metal chelates

A transition metal chelate is species consisting of a transition metal

coordinated (bonded to) one or more ligands (anionic or neutral non-metal

species) or polydentate ligands.

Ligands

Ligands are species (neutral or anionic) bonded to the metal ion. They

may be attached to the metal through a single atom (monodentate) or bonded

to the metal through two or more atoms (bidentate, tridentate.etc.).

Polydentate are called chelating ligands.

Ligands and oxidation state

Low oxidation state complexes can be stabilized by using ligands such

as cyanide and carbon monoxide (π acceptor ligands). Intermediate oxidation

state complexes often have ligands such as chloride, ammonia or water. High

oxidation state complexes usually have fluoride or oxide as ligands. Transition

metal complexes are important in catalysis, materials synthesis,

photochemistry, and biological systems. Display diverse chemical, optical and

magnetic properties.

Coordination number

Coordination number is the number of donor atoms bonded to the

central metal atom/ ion. Transition metal ions usually form complexes with a

well defined number of ligands. Complexes with coordination numbers four

and six are the most common, although two and five coordination are very

well established.


7

Coordination number and geometry are determined by a combination of:

- Metal ion size

- Ligand size - electronic factors (electron configuration, ligand type Linear complexes

Two coordinate linear complexes are almost exclusively found for d10

metal ions such as Ag+, Hg+ etc. These metals can adopt higher coordination

numbers under favorable circumstances. Some linear complexes are shown

in figure – 1.1

Cu (I) x Cu x

X = Cl, Br

Ag (I) H3N Ag NH3 +

Figure 1.1 Linear complexes

Four coordination

Four coordinate chelates typically have a tetrahedral or square planar

geometry. Square planar geometry is only found when there are electronic

reasons for it

Tetrahedral geometry is often found for steric reasons.

- Small metal ion and large ligands.

- Some example of tetrahedral complexes are shown in figure- 1.2


8

OV

OO

O

3-

OCr

OO

O

2

OMn

OO

O

Fe

Cl

ClClCl

Co

Cl

ClClCl

2

Figure1.2. Four coordinate complexes

Square planar complexes

Square planar coordination is rarely encountered for metals that do not

have a d8 electron configuration. For 3d metals this d8 configuration has to be

combined with a π accepter ligand, giving a large crystal field splitting, to get

square planar coordination. Some examples of square planar complexes are

shown in figure – 1.3

PdClCl

Cl Cl

2

PtNH3H3N

H3N NH3

2

AuClCl

Cl Cl

Figure 1.3 Square planar complexes


9

Five coordinate complexes

There are two common geometries for five coordinate complexes:

Trigonal bipyramidal and square pyramidal.

- TBP is sterically favored over square pyramidal.

- Energetic difference between the two geometries is small.

- Geometry can be dictated by the use of an appropriate ligand or by crystal

packing requirements. Examples of five coordinated complexes are

shown in figure – 1.4

Ni

CN

CN

CN

NC

NC

3

[Ni (CN) 5] 3-square pyramidal conformational

Ni

3

NC

NC

CN

CN

CN

Cu

3

Cl

Cl

Cl

Cl

Cl

[Ni (CN) 5] 3-trigonal bipyramidal conformational & [Cu (Cl) 5] 3-trigonal bipyramidal

conformational

Figure 1.4 Trigonal bipyramidal and square pyramidal complexes


10

Six coordinate complexes

By far the most common six coordinate geometry is octahedral, but

various distortions of the octahedral geometry and trigonal prismatic

coordination can be found. Example of six coordinated complexes is shown in

figure – 1.5A &1. 5B.

M

[Co (NH3)6]3+ Regular octahedral

M

Trigonal antiprism

M

Trigonal prismatic

Figure – 1.5 A. Six coordination complexes


11

(A) (B)

(C) (D) Figure –1.5B. (A) And (B) tetragonal distortations of a regular octahedral. (C)

Rhombic and (D) trigonal distortations

Trigonal prismatic coordination

Found in sulfide materials such as MoS2 and in complexes where the

ligand is small relative to the metal center (octahedral is sterically favored

over prismatic) or where special ligands are used. Some examples of trigonal

prismatic coordination are shown in figure – 1.6


12

Ligand with a small bite angle tends to favor trigonal prismatic

coordination.

ML

L

Bite angle

Bite angle

Zr

CH3H3C

CH3H3C

Zr(IV)

2-CH3

CH3

W

SS

SS

W(VI)

S

S

Figure – 1.6. Trigonal prismatic complexes

Higher coordination numbers

Some of the early transition metals are large enough to accommodate

more than six ligands. Some examples of 7- coordinate complexes are shown

in figure – 1.7 and 8-coordinate complexes are shown in figure -1.8 and 9-

coordinate complex is shown in figure –1. 9

Pentagonal bipyramidal occurs in [V (CN)7] 4- and [ZrF7] 3-


13

(a) (b)

(c)

Mo

CNCN

NC NC

NC

NC CN

CN

3-

[Mo (CN) 8]3-

Figure - 1.7 (a) pentagonal bipyramid (b) capped octahedron (c) capped

trigonal prism

[Zr (ox) 4] 4 – square antiprismatic [Mo (CN) 8] 3- Dodecahedral

Figure – 1.8 Eight coordinate complex

[ReH9]2-

Figure – 1.9 Nine coordinate complex


14

Schiff bases

Hugo Schiff described the condensation between an aldehyde and an

amine leading to a Schiff base in 1864 1. Schiff base ligands are able to

coordinate metals through imine nitrogen and another group, usually linked to

the aldehyde.

Ar-CHO + Ar’-NH2 → Ar-CH=N-Ar’ + H2O

Schiff base ligands are considered “Privileged ligands” because they

are easily prepared by the condensation between aldehyde and imines. Schiff

base ligands are able to coordinate many different metals and stabilized them

in various oxidation states, enabling the use of Schiff base metal

complexes for a large variety of useful catalytic transformations.

The presence of dehydrating agents normally favors the formation of

Schiff bases. MgSO4 is commonly employed as a dehydrating agent. The

water produced in the reaction can also be removed from the equilibrium

using a dean stark apparatus, when conducting the synthesis in toluene or

benzene. Finally, ethanol at room temperature or in refluxing condition is also

a valuable solvent for the preparation of Schiff bases.

Degradation of the Schiff bases can occur during the purification step.

Chromatography of Schiff bases on silica gel can cause some degree of

decomposition of the Schiff bases, through hydrolysis. It is better to purity the

Schiff base by crystallization.

Schiff bases are stable solids and can be stored without precautions.

Coordination of the metal with bi-or tridentate Schiff bases can produce

dimeric, or a saturated metal complex. Particularly with early transition metals,

which have a tendency to coordinate ligands in an octahedral manner, the

Complexation step realized in situ can produce a saturated octahedral

complex.


15

Importance of Schiff bases

Schiff bases derived from the Salicylaldehyde are well known

polydentate ligands2. Owing to the biological activity and variable bonding

potentialities in forming complexes with metal ions, the coordination chemistry

of Schiff bases has attracted the attention of several investigators3-9. Schiff

bases containing – RC= N – groups have gained importance because of

physiological and pharmacological activities associated with them.

Nitrogen, oxygen and/or sulphur containing ligands have been found to

possess significant biological and pharmacological activities and are used as

fungicides, tuberculostatic and anti carcinogenic agents10.the coordination

behavior of multidonor Schiff base ligands having sulphur-nitrogen donor sites

has received increasing attention because of their potentially ambidentate

nature and pharmacological importance11.

Some amino acid Schiff base complexes derived from o- hydroxyl

aromatic aldehyde are involved in variety of biological process12,13 e.g. as

catalyst of transamination, recemization and carboxylation reactions. it was

suggested that the active intermediates in transamination reactions were

metal Schiff base complexes. Moreover, they were used as radiotracers in

nuclear medicine and as antibacterial and anticancer reagents. Ternary

complexes containing an amino acid as a second ligand are of significance as

they are regarded as potential models for enzyme metal ion substrate

complexes; they have considerable biological activity.14. Some complex

compounds of gold with cysteine, glycine, histidine and tryptophan possess

selective antibacterial activity and low toxicity 15.

During the past decades 16-19 there has been a great deal of interest in

the synthesis and characterization of transition metal Schiff base chelates

because of their importance as catalysts in many reactions such as

carbonylation, hydroformylation, reduction, oxidation, epoxidation, hydrolysis,

in the chemical and petrochemical industry. The catalytic activity has been

reported to depend upon the structure of the Schiff base ligand.


16

Furthermore, binuclear complexes have been found to be better catalysts

than mononuclear complexes20, 21. Mixed-ligand complexes were used as

catalysts22-24.and also as biological models in understanding the structure of

biomolecules and biological processes25. The development of chiral Schiff

base ligands has received considerable attention since Jacobsen and

subsequently, Katsuki reported significant success in the asymmetric

epoxidation of unfunctionlized olefins by chiral Mn (III) Salen Schiff base

catalyst26. The chiral Schiff base complexes of transition metals are very

effective catalysts for asymmetric cyclopropanation and epoxidation of

alkenes; however they have not been developed to a level such that they

have found widespread use in organic synthesis27-30.

Schiff bases assumed new importance because of their antibacterial

and antifungal activities 31. Schiff bases and their metal complexes play a key

role in our understanding of the coordination chemistry of transition metal

ions. They may serve as models for biological important species, and find

applications in biomimetic catalytic reactions 32-33. Schiff bases containing S,

N and O, N donor atoms are important owing to their significant antifungal,

antibacterial and anticancer activity34. Transition metal complexes with

biologically active Schiff base ligands frequently exhibit higher biological

activity and lower toxicity than initial ligands. This makes possible their use in

medicine and biochemistry35. Many organic compounds used in medicine do

not have a purely organic mode of action; some are activated or

biotransformed by metal ions, others have a direct or indirect effect on metal

ion metabolism 36-37.

The Schiff bases derived from Salicylaldehyde and different amines are

considered to be suitable models for B6 vitamins38. Heterocyclic Schiff bases

metal complexes have attracted considerable attention due to their

remarkable antifungal, antibacterial and antitumour activity39-40. Copper di

Schiff bases have anticarcinogenic activity.41, Organo-Cobalt (III) Schiff base

chelates are proposed for combined cancer therapy42. Schiff bases have been

used as corrosion inhibitors43. The Schiff bases being antipyrine derivatives

may passes antibacterial, antiflammatory44, antipyretic and analgesic

activity45. Schiff bases from acylhydrazie and their complexes have strong


17

antitumor and antivirus activities46. A many hydrazones and their complexes

with metals have provoked wide interest in their diverse spectrum of biological

and pharmaceutical activities, such as anticancer, antitumor and antioxidative

activities, as well as the inhibition of lipid peroxidation etc47.

Transition metal complexes with Schiff bases derived from

arolhydrazines are known as potent inhibitors of DNA synthesis and cell

growth. Such complexes are also important for their possible pharmacological

applications48. Substituted pyrimidine derivatives and its Schiff bases with

salicylaldehyde have been reported as antitubercular, antipyretics, anticancer,

antihypertensive, cardiotonic, analgesic and anti- inflammatory drugs as well

as herbicides 49.

Bioinorganic chemistry

The understanding of the role of metal ions in biochemical process has

lead to the emergence of new fields of study, called inorganic biochemistry.

There are number of metal ions involved in biological systems and

there are number of potential coordinating biomolecules. Hence, the

biochemical reaction should involve the formation of metal complexes. The

bioinorganic chemistry is of fundamental importance to the maintenance of

life because all living systems require an adequate supply of more than twenty

elements and of ligands related to these elements. These ingredients are then

composed into essential biochemicals. Metal ions, in limited quantity are

essential for life processes.

Uses of coordination compounds

A chiral Co (salen) has a well established ability to bind oxygen, useful

for the transfer of carbine and for opening epoxides.

Ni (salen) complex can behave as a bifunctional catalyst.

Bis (acetylacetonato) Co (II) and tris (acetylacetonato) Co (II) have

been found to possess fungicidal activity on cotton and linen fabrics50


18

K4 [Fe(CN)6 ] has been used as corrosion inhibitor for metal surface51

Manganese complexes of 2 [ (1-hydroxy -2- naphthallenyl) carbonyl]

benzoic acid are reported to be effective photo stabilizers for

polymers52

Complexes of thiosemicarbazones have been investigated as

medicinal since Domagk et.al.53 Discovered antitubercular activity in

this class of chemicals and have also been studied for antifungal and

antiviral properties.

Sorenson54 has observed that copper complexes of anti-inflammatory

compounds possess greater activity that the ligand themselves.

In petroleum industries transition metal complexes are used as

catalyst.

Ecofriendly dyes are Metal complex of dyes.

Metal complexes of Rh, Ni, Co, Ti, are used as catalyst for

hydrogenation, homogeneous, hydroformylation reaction, asymmetric

epoxidation of allylic alcohols.

Lead poisoning and copper poisoning are treated by injecting EDTA,

so that metal –EDTA complex is extracted in the urine.

Literature survey

Mi Hie Yi et.al 55-56 has been reported the synthesis of series of novel

aromatic diamines containing cyclohexane moieties. They have also

synthesized and characterized soluble polyimides from1, 1 – bis (4-

aminophenyl) cyclohexane derivatives. Jarrahpouret A. A. et.al57 Synthesized

novel azo Schiff base and their antibacterial and antifungal activities.

New multidentate Schiff base 1,4-bis (o-salicyldeneaminophenyl)-1,4-

dioxobutane and its Co(II), Ni(II) and Zn(II) complexes have been synthesized

by Yamanouchi et.al. 58, Urbach F. L. et.al 59 reported neutral tatradentate

Schiff base ligands derived from 1, 3-diamines and pyridine-2-

carboxaldehyde. .Some mixed Schiff base complexes of Cu (II) and Ni(II)

have been synthesized and characterized by elemental analysis, TLC


19

analysis, conductance , magnetic measurements and spectral analysis by

Bhattacharya P.K. et al.60

Syamal A & Kale K.S. have synthesized Cu (II) complexes with some

tridentate dibasic ONO Donor ligands61. Jani Bakul et.al62 Synthesized new

asymmetric tetradentate Schiff bases Cu(II) complexes and characterized

them by magnetic and spectral and elemental analysis. Ahmed I et.al.

Synthesized Cu (II) and Ni (II) complexes with a tetradentate Schiff base

derived from 2- hydroxyl naphthaldehyde and ethylene diamine and

characterized63. Mary Elizabatihe J et.al.64 synthesized some five co-ordinate

binuclear Schiff base Fe (II) complexes, and carried out Spectral and

magnetic study. Iftikar K. et.al65 - studies on bis (p–dimethyl amino

benzylidene) benzidine complexes of trivalent lanthanides. Marvin Illingworth

et al.66 synthesized eight – coordinate Zr (IV) Schiff base complex as a new

reagent for preparing coordination polymers. Co (II) Schiff base complexes as

oxygen carriers have been synthesized by Dian Chen and coworker67.

Mohmed E. M. Emam et.al.68 synthesized and studied physicochemical

parameters of Cu (II) Ni (II) Co (II) Pd (II) UO2(II) complexes with Schiff base

derived from α-benzylmonoxime. Masakazu Hirotsu et.al69 synthesized Mn

(III) complexes with optical active tetradentate Schiff base Ligands. Noboru

Yoshida et.al70 Synthesized Zn (II) metal complex with some bis – N,N- and

N,O- bidentate Schiff bases and chiral packing modes in solid state.

RamanN.et.al.71 Synthesized and characterized Cu (II), Ni (II), Mn (II), Zn (II)

and VO (II) Schiff base complexes derived from o-phenylendiamine and

acetanilide. Patel M.N. et. al. 72 synthesized coordination chain polymers of

some Mn (II) Cu (II), N i(II), Co (II), Zn (II) and Cd (II) metals with 1-carboxy-

1’-hydroxy-2,2’-(1-isonitriloethylidyne-4-nitrilomethylidenephenyl) diphenyl as

a Schiff base.

Non –symmetrical tetradentate vanadyl Schiff base complexes derived

from 1, 2-phenylene diamine and 1, 3 naphthalene diamine as catalysts for

the oxidation of cyclohexane have been synthesized by Daver M. Boghaei

and Sajjad Mohebi73. Canpla Erdal t et.al74 synthesis of mononuclear chelates

with Co (II), Ni(II), Cu(II), and Zn(II) derived from substituted Schiff base, 5-

Hydroxy salicyliden-p-amino acetophenoneoxime. Salen Schiff base metal


20

complexes in catalysis derived by Pier Giorgio cozzi 75.Mono - and Bi -

Nuclear metal complexes of Schiff base hydrazone derived from o-

hydroxylacetophenone and 2-amino–4-hydrazino-6-methylpyrimidine was

synthesized and characterized by Khalil S.M.E. et.al76. Cu (II), Ni (II), Co (II),

Zn (II) and Cd (II) complexes of Schiff base ligands derived from 7-formyl-8-

hydroxyquinoline and diaminonaphthalenes have been synthesized by Ismail

and Tarek77.

Synthesis, characterization and biological activity of Cu(II) complexes

with phenylglyoxal bis(thiosemicarbazones) have been done by Dharmarajan

and Murthy78. Zidan and et.al 79 reported the coordination properties of some

mixed amino acid metal complexes. Sekerci and Temel 80 reported the

synthesis of Mn (II), Co (II), Cu (II) and Zn (II) complexes with Schiff base

derived from condensation of 1, 2-bis (p-aminophenoxyl) ethane with

Salicylaldehyde. Cu (II), Co(II), Ni(II) complexes with Schiff bases derived

from aroylhydrazines have pharmacological applications is reported by Pal S

et.al81.Synthesis and Characterization of Copper (II), Nickel (II) and Cobalt (II)

Chelates with Tridentate Schiff Base Ligands Derived from 4-Amino-5-

hydroxynaphthalene-2,-7-disulfonic Acid was reported by Mehmet Tunel

et.al82. Raman N et.al83 synthesized, microanlytical, molar conductance and

magnetic prosperities and spectral analysis also done of Cu(II), Co(II), Ni(II),

and Zn(II) complexes of Schiff base derived from benzil-2,4-

dinitrophenylhydrazone with aniline.

Synthesis, Characterization and Catalytic Activity of Salen-type Schiff

Base Polychelates have been done by Bansod et.al84. Khan et.al85

synthesized and characterized, unsymmetrical tetradentate Schiff base Mn(II),

Ni(II) and Cu(II) complexes derived from 2,3-diaminophenol and

Salicylaldehyde and 5- bromosalicylaldehyde. Thaker et.al 86Synthesized and

spectroscopic studies of mononuclear mixed ligand Schiff base complexes of

Cu (II). Sen Soma. et.al87 Synthesized and characterized Zn (II), Cd (II),

Co(II), Co(II) and Mn(II) complexes with the Schiff base derived from 2-

dimethylaminoethylamine and o- vanillin. Joseph J. et.al88 synthesized and

characterized and thermal analysis of Mn(II), Co(II), Ni(II), Cu (II), Cd(II) and


21

Hg(II) metal complexes with Schiff bases derived from 3-formyl-4-

hydroxycoumarin and semicarbazone.

Natarajan K. et.al89 was prepared hexa- coordinated Ru (II) complexes

by hydrolytic cleavage of Schiff bases. Masakatsu Shibasaki et. Al90 reported

the utility of a hetrobimetalic Cu- Sm- Schiff base complex as a syn- Selective

catalytic asymmetric Nitro – mannich reaction. Ali M. Ali, Ayman H. Ahmed,

et.al91 Synthesized Co (II), Ni(II), Fe(III) And Pd(II) Schiff base metal chelates

and corrosion inhibition of Schiff base derived from o-toludine. Sancak

Kemal et.al92 Synthesized Cu (II), Ni (II) Fe (II) complexes with a new

substituted (1, 2, 4) triazole Schiff base and also characterized. Dehghanpour

Saeed et.al. 93 Synthesized and characterized Co (II), Ni (II), and Zn (II),

complexes with N, N’-bis (2-nitrocinamaldehyde)-1,2-diiminoethen ligand.

Samanta Brajagopal et.al.94 Synthesize, Structural, Characterization and

biochemical activity study of new Cu (II) Complexes with polydentate

chelating Schiff base ligands. Synthesis, Spectral Characterization and DNA

Cleavage study of heterocyclic Schiff base Zn (II), Co (II), Ni (II) metal

complexes by Raman N. et.al95.Catalytic activity of polymer anchored N, N’-

bis (o-hydroxy Acetophenone) ethylene diamine Schiff base complexes of

Fe(III), Cu(II) and Zn(II) ions in oxidation of phenol have been synthesized

and characterized by Gupta K.C. et.al96. Bis(O-vanillin) benzidine (o-v2bzh2)

as a binucleating ligands: synthesis, characterization and 3D molecular

modeling and analysis of some binuclear complexes of o-v2bzh2 with Cu (II),

Ni (II), Co (II), Mn (II), Zn (II), Sm (III) and UO2(VI) have been reported by

Maurya R C et.al 97.Rubavathy Jaya Priya A et.al 98 have been synthesized,

spectral characterized and antimicrobial activity of Cu (II), Ni (II), VO (II) metal

complexes with quadridentate Schiff base.

Synthesis, characterized by elemental analyses, spectral and thermal

(TGA-DTA) methods, magnetic and conductance measurements and

biological activity of Cr(III),Fe(III), and Co(III), complexes of tetradentate

ONNO Schiff base ligands as 1,4-bis[3-(2-hydroxy-1-naphthaldimine) propyl ]

piperazine and 1,8-bis[3-(2-hydroxy-1-naphthaldimine)-p-menthane have

been repotted by Eren et.al99. Modi et.al100 synthesized tetradentate Schiff

base complexes of VO (IV) and Cu (II) and evaluated them by spectral,


22

coordination and thermal aspects. Hamadi Temel et.al101 Synthesized and

spectroscopy studies of novel transition metal complexes with Schiff base

synthesized from 1,4-bis-(o-aminophenoxy) butane and Salicyldehyde. Ding

Y. et.al.102Synthesized mono and di Schiff base complexes of Ni (II) and

structurally characterized by singal crystal X-ray diffraction studies. Prasad

Archana et.al. 103 Synthesized, spectral and electrochemical studies of Co (II)

and Zn (II) complexes of novel Schiff base derived from Pyridoxal. Azza A.A.

Abu-Hussen et.al.104 Synthesized new mononuclear transition metal

complexes of macrocyclic Schiff bases derived from 1, 1’-diacetylferrocin and

evaluated them by spectroscopic and biologically. Tanmay Chatopadhyay

et.al105have been synthesized and characterized and studies of

photoluminescence of mono and dinuclear Zn (II) complexes of Schiff base

ligands. Patel R. N. et. Al106. Have been done Spectroscopic, structural and

magnetic studies of nickel (II) complexes with tetra- and pentadentate ligands.

Present Work

The research work described in the thesis is in connection with the

experimental, analytical and spectral, thermal, magnetic studies of some

transition metal chelates of some Schiff’s bases. The results of these

investigations are presented in following chapters.

Chapter – 2 contains the experimental methods used for the Synthesis of the

Schiff’s bases and their metal chelates.

Chapter –3 deals with the description of analytical and spectral study of

Schiff’s bases and their metal chelates.

Chapter –4 described the Themogravimetric analysis of the metal chelates. Chapter –5 contains the description of magnetic measurements of metal

chelates.

Chapter – 6 deals with comprehensive summary of the work.


23

References:-

1. Schiff H. Ann.S.uppl, 3 343 (1864)

2. Chakrovali A. Yilmaz I, Ozmen H, Ahmedzade M. Trans. Met.

Chem. 27,171 (2002)

3. Albert A. Nature (London),9,370 (1953)

4. Fox HH, Gibas JT , Motehna A., J. Org. Chem., 21, 349 (1956)

5. Foye WO, Duvall RN. J. Am. Pharma. ASS. Sci. Edn., 47,258 (1958)

6. Issa R.M, El- Shazly M.F, Iskander M.F, Anorg Z. Allg.Chem.,354, 90

(1967)

7. Price J.M. Fed. Proc., 20,233 (1961)

8. Syamal A., Ghanekar V. D. Ind.J.Chem.,16A, 81 (1978)

9. Alcok J.F., Baker R.J., Diamantis A.A., Aust.J.Chem.,25,289 (1972)

10. Singh M.S., Singh A.K., Tawade K., Synth. React. Inorg. Met.-Org.

Chem.,32, 639 ( 2002)

11. Ibrahim S.A., Elwafa M.H., El-Gahami M.A., Hamman A.M., Thabet W.,

Synth. React. Inorg. Met.-Org. Chem., 22, 1401( 1992)

12. Fan Y., Bi C., Li J., Synth. React. Inorg. Met.-Org. Chem.,33, 137(

2003)

13. Shaker A.M., Awad A.M., Nassar LAE., Synth. React. Inorg. Met.-Org.

Chem.,33,103( 2003)

14. El-Said Al, Zidan ASA, El- Meligy M. S. , Aly AAM, Mohammed O. F.

Synth. React. Inorg. Met.-Org. Chem 30, 1373 (2000).

15. Legler A.V., Kazachenko A.S., Pharma.Chem. Jou. 35,501(2001).

16. Khan M.M.T., Halligudi S.B., Shukla S., Shark J., J. Mol. Catal., 57,301

(1990)

17. Aoyama Y., Fujisawa T., Walanav T., Toi H., Ogashi H., Jou. Am.

Chem. Soc. 108,943 (1986).

18. Bhattacharya P.K., Proc. Chem.Sci., 102,247( 1990)

19. Kimura E., Machida r., Kochima M. Jou. Am. Chem. Soc. 106,

5497(1984).

20. Sung K.M., Huh S., Jun M.J., Polyhedron,18,469( 1999)

21. Chatterjee D., Mitra A., Roy B.C., J. Mol. Cat.A.Chem.,161,17 (2000)


24

22. Goldstein A.S., Beer R.H., Drago R.S., J. Am. Chem.

Soc.,116,2424(1994) 23. Boghaei D.M., Mohebi S., Tetrahedron, 58, 5357 ( 2002) 24. Brown R.S., Zamakani M., Sho J.L., J. Am.Chem.Soc., 106, 5222 1984

25. Atkins R., Brewer G., Kokot E., Mockler G.M., Sinn E., Inorg.Chem.,

24, 127(1985) 26. Irie R., Noda K., Ito Y., Katsuki T.M., Tetrahedron Lett. 31, 7345

(1990). 27. Campbell E.J., Nguyen S.T., Tetrahedron Lett. 41, 1221 (2001). 28. Ragaini F., Cenini S. Mol. Cata. A. 144,405, (1999).

29. Corey E.J., Sarshar S. Jou. Am. Chem. Soc. 144, 7938(1992).

30. Krasik P., Alper H. Tetrahedron .50, 4347(1994).

31. Patel M.M., Patel H.R. Jou. Ind. Chem. Soc. 73 , 313 (1996)

32. Mc Aulife C.A. Ashmawy F.M., Cick R.V. Jamess J.J., Jou. Chem.

Soc.,Dalton Trans. 1391 (1985).

33. Ramadan A.M. Jou. Inorg. Biochem. 65, 183(1997)

34. Saxena A., Koacher J.K.,Tondon J.P., Inorg. Nucl. Chem. Lett. 17,229

(1981).

35. Fursina A.B., Pavlov P.A., KoloKolov F.A. Terekhov V.I. Pharma.

Chem. Jou. 36, 65 (2002).

36. Guo Z., Sadler P.J., Angew. Chem. Int. Ed. 38, 1512(1999).

37. Guo Z., Salder P.J. Adv. Inorg. Chem. 49, 183 (1999).

38. Murthy A.S.N., Reddy A.R. Proc. Ind. Acda. Sci., 90, 519 (1981)

39. Salas J.M., Romero M.A., Sanchez P., Quiros M., Coord. Chem. Rev.,

193, 1119 (1999) 40. Raper E., Coord. Chem. Rev., 129, 91 (1994)

41. Miesel R., Weser U., Free Radical Res. Commune., 11 39-51( 2006)

42. Osinsky S.P., Levitin I.Y., Bubnovskaya L.N., Ganusevich I.I.,

Tsikalova M.V., Istomin Y.P., Anticancer Res. Indian J. of cancer, 17,

3457-3462 (1997)

43. Achouri M., kertit S., Salem M., Essassi E.M.,Tellal M.

Bull.Ele.Chem.,14, 462 (1998)


25

44. Radhakrishnan P.K., Madhu N.T. Synth. React. Inorg. Met.-Org.

Chem.30, 1561 (2000).

45. Costisor O., Marcec M. Jori Z. Labadi I., Linert W. Synth. React. Inorg.

Met.-Org. Chem.30, 1489 (2000).

46. Ma Y., Song Q., Huang G., Synth. React. Inorg. Met.-Org. Chem.31,

297 (2001).

47. Yang Z., Synth. React. Inorg. Met.-Org. Chem.30, 1265 (2000).

48. Pal S., Shyamraj D., Pal S., Sreerama S.G., Ind. Jou. Chem. 42,

2352(2003).

49. Mahale V.B. Revanker V.K., Chabanur H.S., Synth. React. Inorg. Met.-

Org. Chem. 31 ,331(2001).

50. Stonner J.H., Baer N.S., Indicator N., J. Paint Technol., 47, 611 (1975)

51. Morral F.R., “Kirk-othmer Encyclopedia of Chemical Technology’’, 3rd

Edn. Grayson M., Eckroth D., Wiley, New York, 6, 495 ( 1979)

52. Rabek J.F., Ranby B., Arct J., Golubski Z., Eur. Polym. J. 18, 81 (1982)

53. Domagk G., Behnisch R., Mietzsh F., Schmidt H., Naturwissenshaften

.33, 315 (1946)

54. Sorenson J.R.T., J. Med. Chem., 19, 135 (1976)

55. Mi Hie. Yi., Wenxi Huang, Moon Young, jinKil-Yeong,Choi

Macromolecules, 30 5606-5611 (1997)

56. Myska, J., Chem. Abstr., 61, 14558 (1964)

57. Jarrahpour A. A., Motamedifar M., Pakshir K., Hadi N., Zarei M.,

Molecules, 9,815-824 (2004)

58. Kuniko Yamanouchi, Ichiro Murase, shoichiro Yamada, Bul. Chem.

Soc. Japan, 45, 2138-2140 (1972)

59. Urbach F. L., Cambell T. G., Inorg. Chem., 12, 1836 (1973)

60. Bhattacharya P.K., Kohli Rakesh Kumar, Bul. Chem. Soc. Japan,

49,2872-2874 ( 1976)

61. Syamal A., Kale K.S., Ind. J. Chem., 16A, 46-48 (1978)

62. Jani Bakul, Bhattacharya P. K., Ind. J. Chem., 18A, 80 (1979)

63. Ahmed I. , Akhtar F., Ind. J. Chem., 20A, 737 (1981)

64. Mary Elizabatihe J., Zacharias P. S., Ind. J. Chem., 24A, 936 (1985)


26

65. Iftikar K, Arvind, Sayeed M., Ahmad N. Ind. J. Chem., 25A, 589-591

(1986)

66. Marvin L., Illingsworth, Arnold L., Rheingold, Inorg. Chem,.26, 4312-18

(1987)

67. Dian Chen, Arthur E., Martell, Inorg. Chem., 28, 2647-52 (1989)

68. Mohmed E.M., Emam, Magdy M., Bekheit, Mahmoud N. H. Moussa,

Abd-El_nasser A., El-Hendawy, Transition metal Chemistry, 19,

117(1994)

69. Masakazu Hirotus, Kiyohiko Nakajima, Masaaki Kojima, Yuzo Yoshikawa, Inorg. Chem., 34, 6173-78 (1995)

70. Noboru Yoshida, Kazuhiko Ichikawa, Motoo Shiro, J.Chem.Soc.,Perkin

Trans.,2, 17-26 (2000)

71. Raman N., Pitchaikani Raja Y., kulandaisamy A., Proc. Indian Acad.

Sci. (Chem.Sci.),113, 183-189 ( 2001)

72. Patel N. H., Patel K. N., Patel M. N., Synth. React. Inorg. Met.-Org.

Chem., 32, 1879-87 (2002)

73. Daver M., Boghaei, Sajjad Mohebi, Tetrahedron, 58,5357-66 (2002)

74. Canpolat Erdal, Kaya Mehmet, Turk J. Chem., 29, 409-15 (2005)

75. Pier Giorgio Cozzi, Chem. Soc. Rev., 33, 410-421 (2004)

76. Khalil S.M.E. Saleem H. S., El-Shetary B.A., Shebl M. J. Coord.

Chem., 55, 883 (2002)

77. Ismail, Tarek M.A., J. Coord.Chem., 58, 141 (2005)

78. Dharmarajan T.S., Murthy N., As. J. Chem., 14, 1325 (2002)

79. Zidan ASA. El-Said AI, El-Meligy M.S., Aly AAM, Mohammed O.F.,

Synth. React. Inorg. Met.-org.Chem.,31,633 (2001) 80. Sekerci M, Temel H, Synth. React. Inorg. Met.-org.Chem., 31,849

(2001)

81. Pal S, Shyamraj D, Sreerama S.G., Ind. J. Chem., 42,2352 (2003)

82. Mehmet Tunel, Selahattin Serin, Synth. React. Inorg. Met.-

org.Chem.,33, 985 ( 2003)

83. Raman N., Ravichandran S., Thangaraja C., J. Chem. Sci.,16,215-219

(2004).

84. Bansod A.D. , Aswar A.S., Polish J. Chem., 80,1615–1622 (2006)


27

85. Khan, Mustayeen. Bouet, Gilles, Trans. Met. Chem., 31,169-175

(2006)

86. Thaker B.T., Surati K.R., Patel P., Parmar S. D., J. Iran. Chem.,

Soc.,3,371 (2006)

87. Sen Soma, Mitra Samiran, Hughes David L., Dalton Trans.,14,1758

(2006)

88. Joseph J., Mehta B. H., Rus. J. Coord. Chem., 33, 124 (2007)

89. Natarajan K., Sukanya D., Michael R. Evans M. Zeller, Polyhedron,26,

4314 (2007)

90. Shibasaki Masakatsu, Matsunaga Shigeki, Handa Shinya,

Gnanadesikan Vijay J. Am. Chem. Soc., 129, 4900 (2007)

91. Ali M. Ali, Ayman H. Ahmed, Tarek A. Mohamed, Bassem H.

Mohamed, Tran. Met. Chem., 32, 461-467 (2007)

92. Sancak Kemal, Er Mustafa, Yasemin Unver, Yildirim Melike,

Degirmencioglu Ismail, Tran. Met. Chem.,32,16-22 (2007)

93. Dehghanpour Saeed, Mahmoudi Ali, Synth. React. Inorg. Met. - Org.

Nano-Met. Chem., 37, 35-40 ( 2007)

94. Samanta Brajagopal, Chakraborty Joy, Choudhury C.R., Struct. Chem.,

18, 33-41 (2007)

95. Raman N., Johnson Raja S., Joseph J., Dhaveethu Raja J., J. Chil.

Chem. Soc., 52,1138-1141 ( 2007)

96. Gupta K. C. Sutar Alkesh K. React. Funl. Poly., 68,12-26 (2008)

97. Maurya R. C., Chourasia J., Sharma P., Ind. J. Chem., 47,517-528

(2008)

98. Rubavathy Jaya Priya A., Rajavel R., Prasad S., Res. J. Chem.

.Environ., 12,65-69 (2008)

99. Eren Keskioglu, Ayla Balaban Gunduzalp, Servet Cete, Fatma

Hamurcu, Birgul Erk, Spectrochemica Acta Part A., 70, 634-640 (2008)

100. Modi C. K., Thaker B. T., J. Therm. Anly. Calorm., 94, 567-577

(2008)

101. Temel Hamdi, Ilhan Salih, Rus. J. Inorg. Chem., 54, 543-547 (2009)

102. Ding Y., Wang F., ku Z. J., Wang L. S., Wang Q. R., Rus. J. Coord.

Chem.35, 360-366 (2009)


28

103. Prasad Archana, Rao Ch.Parameswara, Mohan Swati, Singh Angad

Kumar, Prakash Rajiv, Rao T. R., Synth. React. Inorg. Met. - Org.

Nano-Met. Chem., 39, 129-132 (2009)

104. Azza A.A. Abu-Hussen, Wolfgang Linert. Synth. React. Inorg. Met.-

org. Nano -Met. Chem.,39, 1323 (2009).

105. Chatopadhyay Tanmay, Mukherjee Madhuparna, Kazi Sabnam

Banu, Banerjee Arpita, Eringathodi Suresh, Ennio Zangrando,

Debasis Das J. Coord. Chem., 62, 967-979 ( 2009)

106. Patel R. N., Shukla K. K., Singh Anurag, Choudhary M., Patel D.

K., Juan Niclo´s-Gutie´rrez, Duane Choquesillo-Lazarte. Trans. Met.

Chem., 34, 239–245 (2009)

Studies on metal chelates……………… Chapter-2

29

2.1 Synthesis of Schiff bases

Synthesis of Amine: 1, 1’ bis (4- aminophenyl) cyclohexane [A].

Aromatic amine [A] was synthesized by acid catalyzed condensation of

Cyclohexanone and excess aniline 1-3.Thus, 0101(10.55ml) mole

Cyclohexanone and 0.267 (24.5ml) mole aniline in 25 ml of 35% HCl at 110oC

for 17-18 hours. After, the resultant solution of 1, 1’ bis (4-aminophenyl)

cyclohexane hydrochloride was stared with 1 gm activated charcoal and 50ml

boil water than cooled to room temperature. At room temperature resinous

mass is separated it was filtrate off. The clear red solution was made alkaline

with drop wise addition of 5% NaOH solution, A white presipate of amine [A]

was separated and amine [A] was filtrated ,washed well with hot distilled

water and dried in an oven at 50-60oC. Amine [A] was recrystallized from

benzene to gate light yellow crystals. The yield was 51% and M.P.112oC.The

purity of amine [A] was checked by TLC in CHCl3 –n – Hexane (70:30) solvent

system.

REACTION SCHEME

O

+

NH2

[1] 35 % HCl [2] 5 % NaOH

2 NaCl + 2H2O

0.101Mol0.267Mol

H2N NH2

110oC

17-18 h.


30

Physical constants of amine [A] 1, 1’ bis (4- aminophenyl) cyclohexane

H2N NH2

Table-2.1

Sr.

No.

Molecular

Formula

Molecular

Weight

(gm)

Melting

Point

(o c)

Color

Rf

Value

1 C18H22N2 266 112 Light

yellow 0.59

TLC Solvent system is Ethyl acetate – n-hexane (70:30v/v)


31

Synthesis of Schiff base: (L1-o-v-AH2) 6,6’-(4,4’-(cyclohexane-1,1-diyl)

bis(4,1-phenylene)) bis (azan-1-yl-1- ylidene) bis (methan-1-yl-1ylidene)

bis (2-methoxy phenol)

Schiff base L1-o-v-AH2 was synthesized by condensation of amine [A]

and substituted aromatic aldehydes 4 in ethanol using glacial acetic acid as a

catalyst at reflux temperature. Thus into a 250ml RBF, 50ml solution of 2-

hydroxy -3- methoxy benzaldehyde (7.6 gm, 50 mmol) in hot ethanol and 50

ml solution of 1,1’ bis(4-aminophenyl)cyclohexene (6.65gm, 25 mmol) in hot

ethanol, using 2 ml glacial acetic acid as a catalyst, and reaction mixture was

reflux on water bath for 4-5 hours. A solid mass was separated out on cooling,

it was suction filtrated, washed with sodium bisulfate to remove unreact

aldehydes, water and finally with ethanol. Subsequently dried over anhydrous

CaCl2 in desiccators. The Schiff base is soluble in common solvent like CHCl3,

benzene, CCl4, DMF. The Schiff base was recrystallized from chloroform and

purity was checked by TLC in appropriate solvent system at room

temperature. The yield was 71%. Analytical details are described in Table 3.1,

in chapter- 3 on page 43.

REACTION SCHEME

+

CHO

0.025 mol 0.05 mol

[1]EtOH[2] Glacial Acetic Acid

[3] Reflux 2 -7 hours

H2N NH2

HO

N NHC

OH HO

CH

OCH3 H3CO

H3CO


32

Physical constants of Schiff base (L1-o-v-AH2)

NN

HC

OH HO

CH

OCH3 H3CO

Table-2.2

Sr.

No.

Molecular

Formula

Molecular

Weight

(gm)

Melting

Point

(o c)

Color

Rf

Value

1 C34H34N2O4 534.62 196 Orange 0.53

TLC Solvent system is Ethyl acetate- n-hexane (80:20v/v)


33

Synthesis of Schiff base: (L2 - Sal – AH2)2,2’-(4,4’-(cyclohexane-1,1-

diyl)bis(4,1-phenylene))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)

diphenol

Schiff base L2-Sal – AH2 was synthesized by condensation of amine [A]

and substituted aromatic aldehydes4 in ethanol using glacial acetic acid as a

catalyst at reflux temperature. Thus into a 250ml RBF, 50ml solution of

Salicylaldehyde (5.25ml, 50 mmol) in hot ethanol and 50 ml solution of 1,1’

bis (4-aminophenyl) cyclohexene (6.65gm, 25 mmol) in hot ethanol, using 2

ml glacial acetic acid as a catalyst, and reaction mixture was reflux on water

bath for 4-5 hours. A solid mass was separated out on cooling, it was suction

filtrated, washed with sodium bisulfate to remove unreact aldehydes, water

and finally with ethanol. Subsequently dried over anhydrous CaCl2 in

desiccators. The Schiff base is soluble in common solvent like CHCl3,

benzene, CCl4, DMF. The Schiff bases were recrystallized from acetone, and

purity was checked by TLC in appropriate solvent system at room

temperature. The yield was 69%. Analytical details are described in Table 3.1

in chapter- 3 on page 43.

REACTION SCHEME

+

CHO

OH

0.025 mol 0.05 mol



NN

HC

OHHO

CH

H2N NH2


34

Physical constants of Schiff base (L2 - Sal – AH2 )

NN

HC

OH HO

CH

Table -2.3

Sr.

No.

Molecular

Formula

Molecular

Weight

(gm)

Melting

Point

(o c)

Color

Rf

Value

1 C32H30N2O2 474.57 154 Light

Yellow 0.62

TLC Solvent system is Ethyl acetate - n-hexane (80:20 v/v)


35

Synthesis of Schiff base:(L3 -O-H-Naph.-AH2) 1,1’-(4,4’(cyclohexane-1,1-

diyl)bis(4,1-phenylene))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-

ylidene)dinaphthalen-2-ol

Schiff base L2-Sal – AH2 was synthesized by condensation of amine [A]

and substituted aromatic aldehydes4 in ethanol using glacial acetic acid as a

catalyst at reflux temperature. Thus into a 250ml RBF, 50ml solution of 2-

hydroxy -1- Naphthaldehyde (8.6 gm, 50 mmol) in hot ethanol and 50 ml

solution of 1,1’ bis (4-aminophenyl) cyclohexene (6.65gm, 25 mmol) in hot

ethanol, using 2 ml glacial acetic acid as a catalyst, and reaction mixture was

reflux on water bath for 5-8 hours. A solid mass was separated out on cooling,

it was suction filtrated, washed with sodium bisulfate to remove unreact

aldehydes, water and finally with ethanol. Subsequently dried over anhydrous

CaCl2 in desiccators. The Schiff base is soluble in common solvent like CHCl3,

benzene, 1, 4-dioxane, DMF. The Schiff bases were recrystallized from

benzene and purity was checked by TLC in appropriate solvent system at

room temperature. The yield was 72%. Analytical details are described in

Table 3.1,in chapter- 3 on page 43.

REACTION SCHEME

+

CHO

0.025 mol 0.05 mol



NN

HC

OH HO

CH

H2N NH2

HO


36

Physical constants of Schiff base: (L3 -O-H-Naph.-AH2)

NN

HC

OH HO

CH

Table - 2.4

Sr.

No.

Molecular

Formula

Molecular

Weight

(gm)

Melting

Point

(o c)

Color

Rf

Value

1 C40H34N2O2 574.68 205 Yellow 0.61

TLC Solvent system is Ethyl acetate - n-hexane (80:20 v/v)


37

2.2 Synthesis of Metal Chelates of Schiff bases:

Synthesis of Copper chelates:-

The metal chelates of Schiff bases, L1-o-v-AH2 were synthesized according

literature 5-8 by mixing 1:1 chloroform-ethanol solution (30ml) of Schiff base,

L1-o-v-AH2 (2.673gm,5mmol) with an ethenolic solution (30ml) of metal

acetate (5mmol,0.998gm Cu(CH3COO)2·H2O) in 1:1 mole ratio. The resulting

mixture was refluxed with staring on a magnetic stirrer equipped with heater

for 5-7 hours. On cooling, the colored chelates precipitated out, which was

filtered by suction, washed several times with ethanol and finally with ether,

and dried over anhydrousCaCl2. All metal chelates are insoluble in common

organic solvent but is soluble in DMSO and DMF. The general reaction

scheme for synthesis of all metal chelates is as following. The Same

procedure was adopted with the other ligands. The physical and elemental

analysis are given in table 3.11 in chapter 3 on page 61.

Cu (CH3COO)2 ·H2O + L1-o-v-AH2 →

Cu (L1-o-v-A) .H2O + 2 CH3COOH

Synthesis of Nickel chelates:-

The metal chelates of Schiff bases, L1-o-v-AH2were synthesized according

literature5-8 by mixing 1:1 chloroform-ethanol solution (30ml) of Schiff base,


acetate (5mmol,1.224gm NI(CH3COO)2· 4H2O) in 1:1 mole ratio. The resulting





organic solvent but is soluble in DMSO and DMF.


38

The general reaction scheme for synthesis of all metal chelates is as

following. The Same procedure was adopted with the other ligands. The

physical and elemental analysis is given in table 3.14 in chapter 3 on page 70.

Ni (CH3COO)2 ·4H2O+ L1-o-v-AH2→

Ni (L1-o-v-A) 2H2O + 2 CH3COOH +2H2O

Synthesis of Cobalt chelates:-

The metal chelates of Schiff bases, L1-o-v-AH2were synthesized according



acetate (5mmol,1.245gm Co(CH3COO)2· 4H2O)in 1:1 mole ratio. The resulting








analysis is given in table 3.17 in chapter 3 on page 79.

Co (CH3COO) 2 ·4H2O + L1-o-v-AH2→

Co (L1-o-v-A) 2H2O + 2 CH3COOH + 2H2O


39

Synthesis of Zinc chelates:-

The metal chelates of Schiff bases, L1-o-v-AH2 were synthesized according



acetate (5mmol,1.1gm Zn(CH3COO)24H2O) in 1:1 mole ratio. The resulting








analysis is given in table 3.20 in chapter 3 on page 88.

Zn (CH3COO)2 ·4H2O+ L1-o-v-AH2 →

Zn (L1-o-v-A) 2H2O + 2 CH3COOH +2H2O


40

References:

1. Schiff H. Ann. Suppl.; 3, 343, (1864)

2. Mi Hie YI, Wenxi Huang, Moon Young Jin, and Kil–Yeong Choi,

Macromolecules, 30 (19), 5606-5611(1997).

3. Myska,J. Chem. Abstr., 61,14558 (1964)

4. Vogel A. R. Texbook of Practical Organic Chemistry,4Th ed.;

Longman,inc.;New York, (1981).

5. Bhattacharya P.K., Kohli Rakesh Kumar, Bul. Chem. Soc. Japan,

49,2872-2874 ( 1976)

6. Syamal A., Kale K.S., Ind. J. Chem., 16A, 46-48 (1978)

7. Jani Bakul, Bhattacharya P. K., Ind. J. Chem., 18A, 80 (1979)

8. Ahmed I. , Akhtar F., Ind. J. Chem., 20A, 737 (1981)


41


42

CHARACTERISATION OF THE SCHIFF BASES 1. ELEMENTAL ANALYSIS:

The microanalysis of Carbon and hydrogen and nitrogen were

performed on a Vario EL-III analyzer. The result of elemental analysis and

general properties like color, empirical formula and formal weight of Schiff

bases are given in table –3.1 on page No. 43

2. ABSORPTION SPECTRA

The absorption spectra of the Schiff bases solution in chloroform was

recorded on a Simadzu 2401 spectrophotometer. The nature of the absorption

curves are shown in fig. 3.1 on page 44.The result are presented in table 3.2

on page no.45

3. IR SPECTRA

The infrared spectra of the amine A and Schiff bases were recorded

using KBr discs on Perkin Elmer spectrophotometer (PerkinElmer RX1)

between 4000-400 cm-1. The IR spectra are represented as in fig. 3.3 to 3.5

on page 47 - 49.The results are presented in table- 3.4 - 3.6

4. NMR SPECTRAL STUDY:

The nuclear magnetic resonance spectrums of the ligands were

recorded in CDCl3 solution on BRUKER DRX-300 Spectrometer [300MHz].

The results obtained are presented in table – 3.7- 3.9 on page no.50-52.

The nature of the NMR spectra shown in fig. 3.6 -3.8 on 50-52

5. MASS SPECTRAL STUDY:-

The mass spectrums of the Schiff bases were on Jeol 102 / Da-600

mass spectrometer at room temperature. Corresponding mass spectra are

shown in fig 3.9 - 3.11 on page 53-55.


43

TABLE – 3.1

ELEMENTAL ANALYSIS OF SCHIFF BASES

Sr. No.

Schiff bases

Molecular Formula

Collar formula Weight (gm)

% of Carbon %of Nitrogen %of Hydrogen

found calculate found calculate found calculate

1 L1-o-v-AH2 C34H34N2O4 Orange 534.62 76.31 76.37 5.18 5.23 6.38 6.41

2 L2 - Sal – AH2 C32H30N2O2 Light

Yellow 474.57 80.92 80.98 5.86 5.90 6.32 6.37

3 L3 -O-H-Naph.-AH2 C40H34N2O2 Yellow 574.68 83.52 83.59 4.80 4.87 5.93 5.96


44

FIG. 3.1 UV SPECTUM OF SCHIFF BASES


45

TABLAE – 3.2

Absorption maximum (λ max.) of the Schiff bases.

Sr. No.

Schiff’s bases λ max[nm]

1 L1-o-v-AH2 326

282

2 L2 - Sal – AH2 346

273

3 L3 -O-H-Naph.-AH2

464.50

444.00

264.00


46

FIG. 3.2 IR Spectrum analysis of amine A

TABLE –3.3

Type Vibration mode

Frequency cm-1

Ref.

Observed Reported

Primary amines

-NH2

v(OH) N-H aym. N-H sy. N-H def. C-N str. N-H wag.

3340.5 3211.3

3421.7

1624

1276.8

819.7

3550-3350

3450-3250

1650-1580

1340-1250

850-750

1-3

Alkane -CH2-

C-H str. (asym.) C-H str. (sym.) C-H def.(asym.) C-H def.(sym.)

2929.3 2854.5 1450.4

1276.8

2975-2920 2880-2860 1470-1435 1395-1370

1-3

Aromatic

C-H str. C=C C-H ( i. p. d. ) C-C ( o. o. p. d. )

1512.1 1276.8 1186.1 1014.5 819.7

1579 ± 5

1258 ± 10

1175 ± 5 817 ± 14

1-3


47

FIG. 3.3 IR Spectrum analysis of Schiff base L1-o-v-AH2

Instrument: Perkin Elmer FT-IR Spectrophotometer Frequency range: 4000-400cm-1

TABLE – 3.4

Type Vibration mode

Frequency cm-1

Ref.

Observed Reported

Hydroxyl-OH

O-H str.

O-H def.

3450.3

1406.3

3650-2590

1410-1310 1-3

Alkane CH3


2936.0 2865.7 1463.8 1365.0

2975-2920 2880-2860 1470-1435 1395-1370

1-3

Aromatic


3068.5 1509.6 1082.5 828.4

3100-3000 1585-1480 1125-1090

860-810

1-3

Schiffs base

N=C str. C-N def.

1615.7 1255.7

1650-1580 1350-1200

1-3


48

FIG.3.4 IR Spectrum analysis of Schiff base: L2 - Sal – AH2


TABLE -3.5

Type Vibration mode

Frequency cm-1

Ref.

Observed Reported

Hydroxyl-OH O-H str.

O-H def. 3451

1407.7

3650-2590

1410-1310 1-3

AlkaneCH2


2925.9 2869.1 1454.7 1396

2975-2920 2880-2860 1470-1435 1395-1370

1-3

Aromatic


3060 1572.3 1114.5

830

3100-3000 1585-1480 1125-1090

860-810

1-3

Schiffs base

N=C str. C-N def.

1626.7 1277.7

1650-1580 1350-1200

1-3


49

FIG.3.5 IR Spectrum analysis of Schiff base: L3 -O-H-Naph.-AH2


TABLE- 3.6

Type Vibration mode

Frequency cm-1

Ref.

Observed Reported

Hydroxyl-OH O-H str.

O-H def. 3426.9 1326.1

3650-2590

1410-1310 1-3

AlkaneCH2


2930.7 2864.5 1498.9 1246.2

2975-2920 2880-2860 1470-1435 1395-1370

1-3

Aromatic


3041.0 1571.5 1085.1 822.8

3100-3000 1585-1480 1125-1090

860-810

1-3

Schiffs base

N=C str. C-N def.

1621.0 1173.7

1650-1580 1350-1200

1-3


50

FIG.3.6 : 1H NMR SPECTRA OF Schiff base L1-o-v-AH2

TABLE – 3.7

Sample NMR chemical shifts, ppm

L1-o-v-AH2

OCH3HO

d

ef

1.504 , 6H,s β +γ –CH2

2.329-2.511, 4H s α –CH2

3.853 ,6H s –OCH3

6.472-6.493 2H f Ar-Hf

6.881 2H e Ar-He

6.97 2H d Ar Hd

7.109-7.1229 4H d Ar Hb

7.199 -7.246 4H d Ar Ha

8.912 2H s CH=N

13.3175 2H s Ar-OH


51

FIG.3.7 : 1H NMR SPECTRA OF Schiff base L2 - Sal – AH2

TABLE 3.8


L2-sal-AH2

HOd

e

fg

1.5837 ( 6H, s, β + γ, -CH2),

2.1731 (4H, s, α, - CH2)

6.936 -6.883 (2H, dd , Ar- Hd ,

7.016-6.966 (2H,dd, Ar-Hf ,

7.222-7.187 (4H,d, Ar-Hb,

7.371-7.319 (8H, m, Ar-H (a+e+g),

8.578 (2HC, s, -CH=N-),

13.365 (2H, s, Ar-OH (h))


52

FIG. 3.8 1H NMR SPECTRA OF Schiff base L3-O-H-Naph.-AH2

TABLE- 3.9


L3-O-H-Naph.-AH2

ΗΟ

d

e

f

gh

i

1.59 ( 6H, s, β + γ, -CH2),

2.301 (4H, s, α, - CH2)

7.16 ( 4H, s Hb Ar-Hb)

7.26 (4H, s Ha Ar-Ha)

7.27 -7.80 (12H ,m d+e+f+g+h+i )

8.38 (2HC, s, -CH=N-),

13.167 (2H, s, Ar-OH


53

FIG. 3.9 MASS SPECTRUM OF SCHIFF BASE L1-o-v-AH2


54

FIG. 3.10 MASS SPECTRUM OF SCHIFF BASE L2 - Sal – AH2


55

FIG. 3.11 MASS SPECTRUM OF SCHIFF BASE L3-O-HNaph.-AH2


56


57

Characterization of Cu (II) Schiff bases metal chelates 1. Solubility:

All Cu (II) Schiff bases metal chelates are insoluble in water and common

organic solvent like chloroform, benzene, ether, ethanol and other organic

solvents .it is soluble in DMF, DMSO

The chelates do not show clear melting point. It gets char at temperature

above 3100 C

2. Conductivity Measurements:

The conductance data for co-ordination compounds provides unimportance

experimental evidence in determining the nature of co-ordination compounds

(whether ionic or covalent).The conductivity of copper chelates was

determined using systronics conductivity bridge model no.361.since the

solubility of chelates is less in common organic solvents. 0.001M solution in

DMSO was used to measured conductivity. The molar conductivity was

calculated using the formula

Molecular conductivity = 1000 x K

C

Where, K = Conductivity of the solution of the metal chelates in DMSO.

C = Concentration of the chelates.

The result is presented in Table 3.10 on page no. 60 the low

conductivity conforms the copper chelates are non-ionic in nature.

3. Molecular Weight Determination:

Because of the less solubility of the metal chelates under study in common

organic solvent the molecular weight of Cu (II) Schiff bases chelates was

determined by Rest’s Camphore method.


58

Rest’s Method:

About 50 mg. of chelates was weighted in a test tube. About 200mg. of

the camphor was added and weighed again. The test – tube was corked

loosely and heated gently on a flame to obtain a clear homogeneous solution.

The tube is shaken and allowed to cool. a small portion of the solidified

mixture is taken, powdered and its melting point determined. The

determination of melting point is repeated to get consistent results. The

melting point of pure camphor is also determined so that the depression in the

melting point can be calculated.

The same experiment is repeated with a known compound, i.e., naphthalene

and the value of k calculated for camphor. The molecular weight was

calculated by using the formula.

M = K x w x 1000

t x W

Where, K = Molecular depression constant

w = weight of complex W = weight of camphor t = Depression of the melting point The result is presented in table -3.10 on pages No.60 4. Elemental Analysis:

This involved the estimation of, copper, Carbon, hydrogen and nitrogen

present in the complex. C, H, and N were performed on a Vario EL-III

analyzer. for copper estimation a known weight of chelates was broken down

in sixty percent A.R. perchloric acid on heating till a clear solution was

obtained, it was transferred to 250 ml. measuring flask and the total volume

was made to 250ml by adding required amount of distilled water. From this

solution copper was estimated complexometrically with EDTA, carbon,


59

hydrogen and nitrogen were estimated on Vario EL-III analyzer the result is

given in table 3.10 on page No.60. 4-5

5. Absorption Spectra of Cu (II) Schiff bases chelates:

The compounds containing transition metal exhibit a great range of

colors of varying intensity. Thee colures arise from the characteristic

absorption in the visible part of the electromagnetic spectrum. The

characteristics visible absorption spectra of the complexes as usually arise

due to electronic transition in the d- orbitals of the metal ions and therefore

they are known as d-d spectra. The d- orbitals in oh or d4h symmetry are of

type g and hence these electronic transitions amongst d- orbitals are Laport-

forbidden transitions and hence are of low intensity but they are allowed by

spin selection rule. The organic part of the ligand shows characteristic

absorption maxima in UV region. From spectral properties of the metal

complexes as well as the effect of spectral studies information in collected

regarding the different substitution in the ligand molecule. The copper

complex of known weight dissolved in DMSO and thus known concentration

solution was prepared.

Absorption spectra of copper complex of Schiff’s bases was taken

using Simadzu 2401 spectrophotometer the nature of the absorption curves

are shown in fig. 3.12 on page -61.the results are summarized in Table 3.11

on page no. 62.

6. IR SPECTRA:

The infrared spectra of the Schiff’s bases Cu (II) metal chelates were

recorded using KBr discs on Perkin Elmer spectrophotometer (PerkinElmer

RX1) between 4000-400 cm-1

. The IR spectra are represented as in fig.3.13 –

3.15 on page no.63-65. The results are presented in table-no.3.12 on page

no.66.


60

TABLE – 3.10

PHYSICAL AND ELEMENTAL ANALYSIS OF Cu (II) METAL CHELATES

Sr. No.

Metal chelates

Molecular Formula

formula Weight (gm)

Collar

Decomposition temp Co.

Yield Conductivity mohs .cm2.mol-1

% Found(calculated)

C H N Metal %

1 Cu(II)(L1-o-v-A)2H2O

Cu(C34H36N2O6) 632.17 Leaf

green >310 66 12.5

64.51 (64.59)

5.71

(5.73)

4.39

(4.43)

10.01

(10.05)

2 Cu(II)(L2 -Sal –A)2H2O

Cu(C32H32N2O4) 572.12 Light green

>318 62 11.8 67.13

(67.17) 5.60

(5.63) 4.85

(4.89) 11.07

(11.10)

3 Cu(II)(L3 -O-H-Naph.-A) 2H2O

Cu (C40H36N2O4) 672.23 Dark green

>310 65 8.6 71.42

(71.46) 5.35

(5.39) 4.13

(4.16) 9.43

(9.45)


61

FIG.3.12 ABSORPTION SPECTRA OF THE Cu (II) METAL CHELATES


62

TABLE – 3.11

Absorption Maximum (λ Max) of Cu (II) Schiff bases metal chelates.

Sr.No. Metal chelates λmax.(nm.)

1 Cu(II)( L1-o-v-A)2H2O

597.00

372.00

277.50

257.50

2 Cu(II)( L2 - Sal – A)2H2O

727.00

401.00

306.00

257.50


411.00

304.00

257.00

221.00


63

Fig. 3.13 IR SPECRA OF Cu (II) L1-o-v-A .2H2O


64

Fig.3.14. IRSPECRAOF Cu (II) L2 - Sal – A 2H2O


65

Fig.3.15 IR SPECRA OF Cu (II) L3 -O-H-Naph.-A 2H2O


66

TABLE – 3.12

Infrared spectral data of the Cu (II) metal chelates

Compounds ν (C=N)cm-1

ν(C-O) cm-1

ν (M-N)cm-1

Cu(II)(L1-o-v-A) .2H2O 1607.5 1441.7 551.0

Cu(II)(L2 –Sal A)2H2O 1610.5 1444.7 553.0

Cu(II)( L3 -O-H-Naph.-A) 2H2O 1612.0 1321.6 521.5


67

Characterization of Ni (II) Schiff bases metal chelates 1. Solubility:

All Ni (II) Schiff bases metal chelates are insoluble in water and

common organic solvent like chloroform, benzene, ether, ethanol and

other organic solvents .it is soluble in DMF, DMSO

The chelates do not show clear melting point. It gets char at

temperature above 3100 C


The conductance of Ni (II) Schiff bases metal chelates was

determined by the method as described on page 57. The result is

presented in Table -3.13. On page 69. The low conductivity conforms the

Nickel chelates are non-ionic in nature.


Because of the less solubility of the metal chelates under study in

common organic solvent the molecular weight of Ni (II) Schiff’s bases

chelates was determined by Rest’s Camphor method. The method as

described on page 57-58. The result is presented in Table -3.13 on page –

69.

4. Elemental Analysis:

This involved the estimation of nickel, Carbon, hydrogen and

nitrogen present in the Schiff base Ni (II) complex, Carbon, hydrogen and

nitrogen present in the complex was performed on a Vario EL-III analyzer.

For nickel estimation using the method as described on page 58.The result

is given in table-3.13. On page No. 69.


68

5. Absorption Spectra of Ni (II) Schiff’s base’s chelates:

The absorption Spectra of Ni (II) Schiff bases metal chelates were

taken using Simadzu 2401 spectrophotometer. The nature of the

absorption curves are shown in fig. 3.16 on page no.70. The results are

summarized in Table -3.14.On page 71.

6. IR SPECTRA

The infrared spectra of the Ni (II) Schiff bases metal chelates were

recorded using KBr discs on Perkin Elmer spectrophotometer

(PerkinElmer RX1) between 4000-400 cm-1. The IR spectra are

represented as in fig. 3.17 - 3.19.On page no.72-74. The results are

presented in table- 3.15 on page no.75.


69

TABLE – 3.13

PHYSICAL AND ELEMENTAL ANALYSIS OF Ni (II) METAL CHELATES

Sr. No.

Metal chelates

Molecular Formula

Molecular Weight (gm)

Collar Decomposition

temp o C.


% Found(calculated)

% C

H

N

Metal

1 Ni(II)(L1-o-v-A)2H2O Ni(C34H36N2O6) 627.34 Green yellow

>310 63 6.3 65.04

(65.09)

5.74

(5.78)

4.40

(4.46)

9.31

(9.35)

2 Ni(II)(L2 -Sal -A)2H2O

Ni(C32H32N2O4) 567.29 Light green yellow

>325 61 7.6 67.69

(67.74) 5.66

(5.68) 4.90

(4.93) 10.32

(10.34)

3 Ni(II)( L3 -O-H-Naph.-A) 2H2O

Ni (C40H36N2O4)

667.40 Green yellow

>320 65 7.9 71.92

(71.98) 5.40

(5.43) 4.15

(4.19) 8.76

(8.79)


70

FIG.3.16. ABSORPTION SPECTRA OF THE Ni (II) METAL CHELATES


71

TABLE – 3.14

Absorption Maximum (λ Max) of Ni (II) Schiff bases metal chelates.


1 Ni(II)( L1-o-v-A)2H2O

754.00

404.00

308.00

259.00


349.00

325.00

270.00


326.00

282.00

252.00


72

Fig.3.17 IR SPECRA OF Ni (II) L1-o-v-A 2H2O


73

Fig.3.18 IR SPECRA OF Ni (II) L2 - Sal – A 2H2O


74

Fig. 3.19 IR SPECRA OF Ni (II) L3 -O-H-Naph.-A 2H2O


75

TABLE – 3.15

Infrared spectral data of the Ni (II) metal chelates


ν(C-O) cm-1

ν (M-N)cm-1

Ni(II)( L1-o-v-A )2H2O 1608.5 1440.7 543.0

Ni(II)(L2 –Sal A)2H2O 1615.1 1444.5 547.8

Ni(II)( L3 -O-H-Naph.-A ) 2H2O

1611.2 1327.1 519.5


76

Characterization Of Co (II) Schiff bases metal chelates 1. Solubility:

All Co (II) Schiff bases metal chelates are insoluble in water and

common organic solvent like chloroform, benzene, ether, ethanol and

other organic solvents .it is soluble in DMF, DMSO

The chelates do not show clear melting point. It gets char at

temperature above 3000 C


The conductance of Co (II) Schiff bases metal chelates was

determined by the method as described on page 57. The result is

presented in Table -3.16.On Page no. 78. The low conductivity conforms

the cobalt (II) chelates are non-ionic in nature.


Because of the less solubility of the metal chelates under study in

common organic solvent the molecular weight of Co (II) Schiff bases

chelates was determined by Rest’s Camphor method. The method as

described on page no. 57-58. The result is presented in Table -3.16.on

page no.78.


This involved the estimation of Cobalt, Carbon, nitrogen and

hydrogen present in the Schiff bases Co (II) complexes, Carbon, hydrogen

and nitrogen present in the complex was performed on a Vario EL-III

analyzer. For Cobalt estimation using the method as described on page

on.58.The result is given in Table–3.16. On page No. 78.


77

5. Absorption Spectra of Co (II) Schiff bases chelates:

The absorption Spectra of Co (II) Schiff bases metal chelates were

taken using Simadzu 2401 spectrophotometer. The nature of the

absorption curves are shown in fig.3.20 on page no.79.The results are

summarized in Table –3.17. On page 80.

6. IR SPECTRA

The infrared spectra of the Co (II) Schiff bases metal chelates were

recorded using KBr discs on Perkin Elmer spectrophotometer

(PerkinElmer RX1) between 4000-400 cm-1

. The IR spectra are

represented as in fig.3.21 – 3.23 on page no.81 -83. The results are

presented in table-3.18 on page no.84.


78

TABLE – 3.16.

PHYSICAL AND ELEMENTAL ANALYSIS OF Co (II) METAL CHELATES

Sr. No.

Metal chelates

Molecular Formula


Collar

Decomposition

temp o C.


% Found(calculated)

% C

H

N

Metal

1 Co(II)( L1-o-v-

A)2H2O Co (C34H36N2O6) 627.56 orange >300 65 8.1

65.00 (65.06)

5.75

(5.78)

4.43

(4.46)

9.32

(9.39)

2 Co(II)(L2 -Sal –

A)2H2O Co (C32H32N2O4) 567.51

Brown orange

>315 62 5.9 67.68

(67.72) 5.63

(5.68) 4.90

(4.93) 10.35

(10.38)

3 Co (II)( L3 -O-H-Naph.-A) 2H2O

Co (C40H36N2O4) 667.62 Dark

orange >320 64 6.6

71.91 (71.95)

5.40 (5.43)

4.15 (4.19)

8.79 (8.82)


79

FIG 3.20.ABSORPTION SPECTRA OF THE Co (II) METAL CHELATES


80

TABLE – 3.17

Absorption Maximum (λ Max) of Co (II) Schiff bases metal chelates.


1 Co (II)( L1-o-v-A)2H2O

505.00

314.00

255.00

2 Co (II)(L2 -Sal -A)2H2O

561.00

302.50

256.00

3 Co (II)( L3 -O-H-Naph.-A) 2H2O

538.00

303.00

257.00


81

Fig.3.21 IR SPECRA OF Co (II) L1-o-v-A 2H2O


82

Fig.3.22 IR SPECTRA OF Co (II) L2 - Sal – A 2H2O


83

Fig.3.23 IR SPECRA OF Co (II) L3 -O-H-Naph.-A 2H2O


84

TABLE – 3.18

Infrared spectral data of the Co (II) metal chelates

Metal chelates

ν (C=N)cm

-1 ν(C-O) cm

-1 ν (M-N)cm

-1

Co(II)( L1-o-v-A )2H2O 1614.5 1445.4 501.2

Co (II)(L2 –Sal A)2H2O 1608.8 1436.0 500.8

Co(II)(L3 -O-H Naph.-A) 2H2O 1612.2 1329.0 515.2


85

Characterization of Zn (II) Schiff bases metal chelates 1. Solubility:

All Zn (II) Schiff bases metal chelates are insoluble in water and common

organic solvent like chloroform, benzene, ether, ethanol and other organic solvents

.it is soluble in DMF, DMSO

The chelates do not show clear melting point. It gets char at temperature

above 3000 C


The conductance of Zn (II) Schiff bases metal chelates was determined by

the method as described on page no.57.The result is presented in Table -3.19 on

page no.87.The low conductivity conforms the Nickel chelates are non-ionic in

nature.


Because of the less solubility of the metal chelates under study in common

organic solvent the molecular weight of Zn (II) Schiff bases chelates was determined

by Rest’s Camphor method. The method as described on page no.57-58.The result

is presented in Table -3.19.On pageno.87.


This involved the estimation of Zinc, Carbon, nitrogen and hydrogen present

in the Schiff base Zn (II) complex. Carbon, hydrogen and nitrogen present in the

complex were performed on a Vario EL-III analyzer. For Zinc estimation using the

method as described on page 58.The result is given in Table –3.19 on pages No.87.


86

5. Absorption Spectra of Zn (II) Schiff bases chelates:

The absorption Spectra of Zn (II) Schiff bases metal chelates were taken

using Simadzu 2401 spectrophotometer. The natures of the absorption curves are

shown in fig. 3.24 on page no. 88.The results are summarized in Table –3.20 on

page -89.

6. IR SPECTRA

The infrared spectra of the Zn (II) Schiff bases metal chelates were recorded

using KBr discs on Perkin Elmer spectrophotometer (PerkinElmer RX1) between

4000-400 cm-1

. The IR spectra are represented as in fig. 3.25-3.27 on pages 90 - 92.

The results are presented in Table-3.21 on page no.93.


87

TABLE – 3.19

PHYSICAL AND ELEMENTAL ANALYSIS OF Zn (II) METAL CHELATES

sr.

No.

Metal chelates

Molecular Formula


Collar

Decomposition

temp o C.


% Found(calculated)

% C H N Metal

1 Zn(II)( L1-o-v-A)2H2O Zn(C34H36N2O6) 634.00 Yellow >315 62 2.9 64.36

(64.40)

5.69 (5.72)

4.38

(4.41)

10.27

(10.31)

2 Zn (II)(L2-Sal–A)2H2O Zn(C32H32N2O4) 573.95 Light

yellow >310 61 7.1

66.91 (66.96)

5.58 (5.61)

4.83 (4.88)

11.35 (11.38)

3 Zn (II)(L3 -O-H-Naph.-A) 2H2O

Zn(C40H36N2O4) 674.06 Light

yellow >325 60 4.6

71.22 (71.26)

5.35 (5.38)

4.11 (4.15)

9.65 (9.69)


88

FIG. 3.24 ABSORPTION SPECTRA OF THE Zn (II) METAL CHELATES


89

Table – 3.20

Absorption Maximum (λ Max) of Zn (II) Schiff bases metal chelates.


1 Zn(II)( L1-o-v-A)2H2O

414.00

325.00

258.00

2 Zn(II)(L2 -Sal A)2H2O

347.00

271.00

3 Zn(II)(L3 -O-H-Naph.-A) 2H2O

325.00

281.50

251.00


90

Fig. 3.25 IR SPECRA OF Zn (II) L1-o-v-A. 2H2O


91

Fig.3.26 IR SPECRA OF Zn (II) (L2 - Sal – A) 2H2O


92

Fig.3.27 IR SPECRA OF Zn (II) (L3 -O-H-Naph.-A) 2H2O


93

Table – 3.21

Infrared spectral data of the Zn (II) metal chelates


ν(C-O) cm-1

ν (M-N)cm-1

Zn(II)( L1-o-v-A )2H2O 1614.3 1459.3 570.3

Zn (II)(L2 –Sal A)2H2O 1610.2 1453.9 576.6

Zn(II)(L3 -O-H Naph.-A) 2H2O

1611.0 1392.1 571.0


94

References:

1. V.M. Parikh; “absorption spectroscopy of organic Molecule” .Addition-

Wesley Pub. Co. London,243-256(1978)

2. C. N. R. Rao; “chemical application of infrared spectroscopy” Academic

press, New York (1963).

3. Silverstein Bassler and Morrill; spectrometric identification of organic

compounds 5th edn. By john wiely & sons Inc.(1991).

4. Vogel A. I.; “Quantitative Inorganic Analysis”, Longamans Green,

London, (1961).

5. Schwarzenbach G. “complexomeric titration” Intersciences, New York,

76, (1960).


95

General

Le Chatelier 1, 2 was the first to use thermal transformation of materials

as an analytical tool. He applied this technique to analyze the clay materials.

A number of investigators have obtained kinetic information from DTA

measurements3, 4. Murray and white 5 reported that the thermal decomposition

of clay followed a first order law. Kissinger 6 studied the variation of peak

temperature with heating rate in DTA. The application of DTA to organic

material offers considerable potential to the study of thermal properties, which

are important from both scientific and practical point of view.

Still 7has classified the thermal method of analysis into different

categories depending on change in weight, in dimension and those involving

evolved volatiles. The techniques based on energy changes are DTA and

DSC. Those depending on weight change are TGA and isobaric and

isothermal weight change. Differential and derivative dilatometry are the

example of techniques base on dimensional changes where as the

techniques depending upon the evolved volatiles are evolved gas detection

(EGD) and evolved gas analysis(EGA).the parameters measured as a

function of temperature in DTA , TGA, DSC. Physical transformation such as

melting, freezing, volatilization, glass transformation, crystallization from

melts, etc., can be studies by DTA and DSC.

Chemical transformation 8can is studies by DTA and TGA. In DTA

technique, difference in temperature between a substance and reference

materials is recorded against either temperature or time as the two specimens

are subjected to identical temperature regimes in an environment heated or

cooled at a controlled heating rate. Any transition, which a sample undergoes,

will result in absorption or liberation of energy by the sample with a

corresponding deviation of its temperature from that of the reference. In DTA,

when at a particular temperature, sample change its physical or chemical

state, the differential signal appears as a peak. The numbers, position, shape

and nature (exothermic or endothermic) of peak gives information about


96

melting crystallization, glass transition temperature, crystalline rearrangement,

decomposition of the compound,etc9

Thermal analysis is defined as a group of methods based on the

determination of changes in chemical or physical properties of material as a

function of temperature in a controlled atmosphere. Thermo gravimetric

analysis (TGA), measures weight loss or gain. There are three types of

thermogravimetry: static or isothermal thermogravimetry, Quasistatic

thermogravimetry and dynamic thermogravimetry .generally dynamic

thermogravimetry is used. In this technique, the sample start losing weight at

a very slow rate up to a particular temperature and then the rate of weight loss

become large over a narrow range of temperature. After this temperature, the

loss in weight levels off. TG curves are characteristic for a given compound

because of unique sequence of physicochemical reaction which occurs over

definite temperature range and at rates that are a function of molecular

structure. The changes in weight are due to rupture and /or formation of

various physical and chemical changes which lead to the evolution of volatile

products or the formation of heavier reaction products10

TGA monitors weight change in material as a function of temperature

(or time) under a controlled atmosphere. This allows measurement of the

thermal stability and composition of a material through. Determination of the

reaction temperature involving weight changes. Such reaction includes

dehydration, solvent /volatile removal, oxidation and decomposition. There are

three types of thermogravimetry: static or isothermal thermogravimetry,

quasistatic thermogravimetry and dynamic thermogravimetry. Generally

dynamic thermogravimetry is used. In this

TGA is routinely used in all phases of research, quality control and

production operations. For example of TGA trace of calcium carbonate

(CaCO3) to 1000oC showing a mass loss of 44% around 850oC.This mass

loss may be associated with the removal of CO2 to form CaO.

In thermogravimatric analysis, a small but accurately known sample

mass (typical about 100 milligrams) is heated in a crucible on an analytical


97

balance during controlled heating. An inert reference material treated

simultaneously ensures that any drift of the instrument can be corrected for. In

general several gases – atmospheres (e.g. air, N2, CO2) can be chosen. Any

difference of weight of the sample (loss or gain) is recorded verses

temperature during controlled heating. This may be related to reaction(s)

taking place in a sample, (such as oxidation, reduction, dehydration etc.). The

technique is suited for many solid materials, although limitation may arise with

respect to possible reactions with the crucible, or corrosive gases emitted by

the sample.

Thermal analysis is a good analytical tool to measure:-

• Thermal decomposition of solids and liquids

• Solid-solid and solid-gas chemical reactions

• Material specification, purity and identification

• Inorganic solid material absorption

• Phase transitions.

• Elastomers

- Evolution possibilities for the glass transition

- Influence of sample pretreatment on the glass transition

- Expansion coefficient of silicone elastomers

- Comparison of different possibilities for evaluating the glass

transition

- Glass transition of vulcanized and unvulcanized silicone

elastomers

- Analysis of carbon black in SBR elastomers with different

degrees of cross-linking

- Analysis of carbon black in elastomers based on chloroprene


98

- TGA of silicone elastomers

- Identification of BR and NBR using a TGA – FTIR combination

- TGA of elastomers containing SBR as one constituent

- Analysis of a CR/ NBR blend by TGA

- Combined TGA and DSC analysis of an EPDM/SBR blend

- Temperature – dependent DMA measurements of an unfilled

SBR/NR elastomer

• Pharmaceutical

The potential applications of thermal analysis in the

pharmaceutical industries are numerous on account of the different

chemical – physical aspects of investigations. Amongst others these

include method development, characterization and specification of

active and inactive ingredients, safety analysis or routing analysis in

quality control and stability studies.

- Melting behavior and decomposition

- DSC fingerprint

- Purity using DSC and HPLC

- Solvent detection by means of TG-MS, Pharmaceutical active

substance

- Quantification

• Thermoplastics

• Food

- TGA of sugar and starch

- DSC of amorphous sugar


99

- Influence of pH on bovine Hemoglobin

- DSC of meat

• Evolved gas analysis

- Decomposition of acetylsalicylic acid

- Detection pf residual solvents in a pharmaceutical substance

- Decomposition of copper sulfate pentahydrate

- Detection of methyl salicylate in sample of rubber

Base on this information, one can characterize polymers, organic or

inorganic chemical, metal, semiconductors and other common classes of

materials.

Analysis of water molecules from thermal decomposition:

The Thermogrvimetric analysis data provide important experimental evidence

in determining the number of water molecules present in the Schiff base metal

chelates. Generally, the loss of lattice water will be at a lower temperature

than that of the coordinated water 11.According to Patel et. al12 Coordinated

water molecules were evaluated by considering the residue loss at 150-200oC

and lattice water molecules were evaluated by considering weight loss at 100

– 110oC. Analytical data of the chelates support the formulations proposed

after evaluation of water molecule.

Literature survey

Khare et al 13 have studied thermal decomposition of ammonium

interacted dcolite; which shows a remarkable exchange capacity with NH4+ion

which replaces 80.71% of Na2O. they observed dehydration, deammoniation

and dehydroxylation processes during thermal treatment of this derivative

thermal studies on some chelate polymers were carried out by Aswer et al 14

and depicted that the decomposition temperature of the polychelates

decrease in the order Ni > Mn > Cu > Co > Zn and concluded that the reaction


100

of decomposition of poly chelates can be classed as a slow reaction.

Upadhyaya et al 15 studied the thermal decomposition of praseodymium and

neodymium myrisates both as a function of temperature and time. The

thermogrvimetric analysis has show that order of decomposition reaction is

kinetically of zero order and the energy of activation for the decomposition

process lies in the range of 10-15 kcal/ mole. Thermal behavior of some

organotin IV) semicarbazone and thiosemicarbazone complexes were studied

by Nath et al 16 .Patel et al 17 prepared some solid complexes of α –

oximinoacetoacet – O / P chloroanilide – β thiosemicarbazone with metal their

characteristic with thermogrvimetric analysis revels that the rate of reaction for

the metal chelates decomposition is faster then the ligand and the metal

chelates follow a single step decomposition. Fluorenone antthranilic acid

complexes of Mn (II), Co (II), and Ni (II) were synthesized by Thomas et al 18.

Thermal studies of dioxouranium (VI) sulphato complexes of some Schiff base

of 4-aminoantipyrine was studied by Agarwal 19 and reported that the TG

curves of these complexes do not show the presence of water molecule either

n or out of the coordination sphere. The thermal analysis of Fe(II) , Ni (II) and

Cu (II) complexes with 1,3,5 – trimethylhexahydrotrizine and 1,4,7-

triazacyclononane were studied by TG and DTA techniques by Belal 20 and

reported their relative thermal stability. Ali et al 21 studied the thermal behavior

of the adduct of 8- hydroxyquionoline and determined the kinetic parameters

such as order of reaction and activation energy, using TG curves. Thermal

decomposition of palladium complexes with triphenylphosphine were studied

by Baobieri et al 22 where as thermal degradation of palladium – di – thioester

systems up to 10000C and their intermediates were studies by Faraglia et al 23

the kinetic properties and thermal stability of chlorinated complexes of Co(II)

and Ni (II) with 3-hydroxypyridine were studied in a N2 atm. Using TGA, DTG

and DSC methods by Halawani 24. Thermal behavior of some divalent

transition metal complexes of triethanolamine was examined by Icbudak et

al25 and by using the initial decomposition temperature the sequence of

thermal stability was found to be Mn(II)> Fe(II) > Ni (II)>Zn(II)>Cu(II). Kinetic

parameters and the reaction between thermal stability and chemical structure

of the complexes also been discussed. In case of some isodithiobivert


101

complexes thermal pattern was used to predict the attachment of metal ion

with sulfur. In this case due to sulfur environment around the metal ion the

formation of metal sulphate or metal were made on the basis of change in

weight of respective residues. Omar, M.; Mohamed, G. et.al.26 examine the

thermal behavior of Transition metal complexes of heterocyclic Schiff base is

studied and the activation thermodynamic parameters are calculated using

Coats-Redfern method. Synthesis, spectral and thermal degradation kinetics

of divalent cadmium complexes studies by Bhojya Naik et.al27.

Discussion

A Representative Thermogram of Cu (II), Co(II), Ni(II) and Zn(II)

chelates is given in fig 4.1 – 4.4, it is found from the TGA that the heating

rates were suitably controlled at 10 o C/min under nitrogen atmosphere and

weight loss was measured from temperature range of 50-800 o C.

Thermogram of metal chelates indicates small weight loss in 60oC to 80oC

which is assigned to loss of lattice water, it has been observed that the Schiff

base metal chelates show a loss in weight corresponding to decomposition of

partial organic ligand with two water molecules is coordinated to the metal ion

in the temperature range 110 oC to 295 oC 28-31. And the gradual weight loss

in the temperature range 295oC - 700oC or 800oC, can be assigned to

complete decomposition of ligand moiety around metal ion. In all cases, the

final products are metal oxides. In all cases, these results are in good

accordance with the proposed Schiff base metal chelates composition. The

Thermal analysis data are collected in table 4.1. On page 102.


102

Table -4.1

Thermogravimetric Data

Sr.No. Metal chelates % Loss in weight

Temp. 0C Found (calcd.)

1 Cu(II)( L1-o-v-A)2H2O 5.65(5.69)a 110-290

87.39(87.41)b 290-800

2 Cu(II)( L2 - Sal – A)2H2O 6.27(6.29)a 110-290

86.02(86.09)b 290-700


5.33(5.35)a 110-275

88.11(88.16)b 275-700

4 Ni(II)( L1-o-v-A)2H2O 5.89(5.92)a 115-190

87.66(87.69)b 190-800


6.30(6.34)a 110-190

86.79(86.83)b 190-800


5.35(5.39)a 110-180

88.75(88.80)b 180-800

7 Co(II)(L1-o-v-A)2H2O 5.88(5.92)a 110-275

87.62(87.66)b 275-700

8 Co(II)(L2 -Sal –A)2H2O 6.30(6.34)a 110-285

86.76(86.79)b 285-700

9 Co (II)(L3 -O-H-Naph.-A) 2H2O

5.33(5.39)a 110-290

88.78(88.83)b 290-700

10 Zn(II)(L1-o-v-A)2H2O 5.82(5.86)a 110-295

86.71(86.74)b 295-700

11 Zn (II)(L2 -Sal –A)2H2O 6.22(6.27)a 110-290

85.78(85.82)b 290-700

12 Zn (II)(L3 -O-H-Naph.-A) 2H2O

5.31(5.34)a 110-285

87.90(87.92)b 285-700


103

Fig. 4.1 Thermogram of [Cu (II) ( L2 -Sal –A- 2H2O) ]


104

Fig. 4.2 Thermogram of [Co (II) (L1-o-v-A - 2H2O) ]


105

Fig. 4.3 Thermogram of [Ni (II) (L3–O-Naph.-A- 2H2O) ]


106

Fig. 4.4 Thermogram of [ Zn(II) ( L2 Sal –A- 2H2O) ]


107

References:

1. H. Le Chatelier, Bull. Soc. Franc. Mineral, 10, 204 (1887).

2. H. Le Chatelier, Z Physik. Chem.., 1,396 (1987).

3. P.Murray and J. White, Clay Mineral Bull., 2, 255 (1955).

4. P.Baumgartner and P.Duhaut, Bull.Soc.Chem. france, 1187 (1960).

5. P.Murray and J. White, Trans. Brit. Ceram. Soc., 48, 187 (1949).

6. H. E. Kissinger, J.Res. Natl. bur. Std., 57, 217 (1956).

7. R.H. Still, British Polymer, L., 11, 101 (1979).

8. E.Heisenberg, Cllulose Chemie, 12,159 (1931).CA, 25, 59823(1931).

9. G.Chatwal and S. anand “instrumental Methods of Chemical Analysis”

Second Edition (1984).

10. H.H. Willard, L.L. Merritt, Jr, J. A. Dean and F. A. Settle,

Jr.,"Instrumental Methods of Analysis” Sixth Edition (1986).

11. Joshi, R. A.: J. Chem. Soc. 21, 259, (1994).

12. Patel P.S., Patel M. M. J. Ind. Chem. Soc. 72, 149 (1999).

13. Khare A. S. Banerjee S.P. J. Ind. Chem. Soc. 68 353 (1991).

14. Aswer A. S., Munshi K. N.Ind. Chem. Soc. 69,544 (1992).

15. Upadhyaya S.K., Sharma S.P., J. Ind. Chem. Soc. 70, 753 (1993)

16. Nath M., Sharma N., J. Ind. Chem. Soc. 72,115 (1995).

17. Patel P.S., Patel M. M. J. Ind. Chem. Soc. 72, 149 (1995).

18. Thomas J. K., Parameshwaran, G. J. Ind. Chem. Soc. 72,155 (1995).

19. Agarwal R. K. J. Ind. Chem. Soc. 72, 263 (1995).

20. Belal A.A.M. Asian Sci. Tech.Bult. 15,59, (1994).


108

21. Ali, S.I., Ansari, A.M.A., Pundhir,N.K.S. Inorg. Bio.-Inorg. Phys.Theor.

Anal. Chem. 34A (6), 423, (1995).

22. Barbieri R.S., Belatto C.R., Massabni A.C. J.Therm.Anal. 44(A), 903

(1995).

23. Farsglia G., Longo D., Cherchi V., Sitran S. Polyhedron 14, 1905

(1995).

24. Halawani K. H. Thermochim Acta 256(2), 359 (1995).

25. Icbudak H., Yilmaz V.T. Oelmez H., J. Therm. Anal. 44(3), 605(1995).

26. Omar M., Mohamed G., Hindy A. J. Of Thermal Anly. And Calorimetry

86(2) ,315-325 (2006).

27. Halehatty S. Bhojya Naik, R. Chetana, D. Revanasiddappa,Turk J.

Chem. 26,565-572(2002)

28. Icbudak H., Yilmaz V.T. Oelmez H., J. Therm. Anal. 53, 843(1998).

29. Issar,Y.M., Abdel Latif S. A., Abu-El-Wafa S. M., Abdel – Salam H.A.

Synth.Reac.Inorg.Met.-Org. Chem.,29(1), 53 (1999).

30. Tumer M. Ko¨ksal H., Sertn S. Synth.Reac.Inorg.Met.-Org. Chem.

27(5), 775 (1997).

31. Nakamoto K. Lattice water and aqua and hydroxo complexes in

infrared and raman spectra of Inorganic and coordination compounds

.4TH Edn.,John wiley and sons, ine., 227.1986.


109

General

Materials may be classified by their response to externally applied

magnetic fields as diamagnetic, paramagnetic, or ferromagnetic, these

magnetic responses differ greatly in strength. Diamagnetic is a property of all

materials and opposes applied magnetic fields, but is very weak.

Paramagnetism, when present, is stronger than diamagnetism and produces

magnetization in the direction of the applied field, and proportional to the

applied field. Ferromagnetic effects are very large; producing magnetizations

sometimes orders of magnitude greater than the applied field and as such are

much larger than either diamagnetic or paramagnetic effects.

The magnetization of material is expressed in terms of density of net

magnetic dipole moments µ in the material. The magnetization (M) is given by

M = µ total / V

Then the total magnetic field B in the material is given by

B = B0 +µ0M

Where µ0 is the magnetic permeability of space and B0 is the externally

applied magnetic field. When magnetic field inside of materials are calculated

using Ampere’s law or the Biot- Savart law, then the µ0 in those equations is

typically replaced by just µ with the definition

µ = Km µ0

Where Km is called the relative permeability. If material dose not

respond to the external magnetic field by producing any magnetization, then

Km = 1. Another commonly used magnetic quantity is the magnetic

Susceptibility which specifies how much the relative permeability differs from

one. Magnetic susceptibility χ m = Km – 1

For paramagnetic and diamagnetic materials the relative permeability

is very close to 1 and the magnetic susceptibility very close to zero. For

ferromagnetic materials, these quantities may be very large.


110

Another way to deal with the magnetic field which arise from

magnetization of materials is to introduce a quantity called magnetic field

strength H. it can be defined by the relationship and has the value of

H = B0 / µ0 = B / µ0 – M

Unambiguously designating the driving magnetic influence from

external currents in a material, independent of the material’s magnetic

response. The relationship for B above can be written in the equivalent from

B = µ0 (H + M)

H and M will have the same units, amperes / meter.

Types of magnetic behavior

(a) Diamagnetism :

Diamagnetism was discovered and named in 1845 by Michael

Faraday.

The orbital motion of electrons creates tiny atomic current loops, which

produce magnetic fields. When an external magnetic field is applied to a

material, these current loops will tend to align in such a way as to oppose the

applied field. This may be viewed as atomic version of Lenz’s law: induced

magnetic field tend to oppose the change which created them. Materials in

which this effect is the only magnetic response are called them. Materials in

which this effect is the only magnetic response are called diamagnetic. All

materials are inherently diamagnetic, but if the atoms have some net

magnetic moment as in paramagnetic materials, or if there is long- range

ordering of atomic magnetic moments as in ferromagnetic materials, these

stronger effects are always dominant.

Diamagnetic is the residual magnetic behavior when materials are

neither paramagnetic nor ferromagnetic.

Diamagnetic is a very weak from of magnetism that is only exhibited in the

presence of an external magnetic field. It is the result of change in the orbital


111

motion of electrons due to the external magnetic field. The induced magnetic

moment is very small and in a direction opposite to that of the applied field.

When placed between the poles of a strong electromagnet, diamagnetic

materials are attracted towards regions where the magnetic field is weak.

Diamagnetism is found in all materials; however, because it is so weak it can

only be observed in materials that do not exhibit other forms of magnetism.

Also, diamagnetism is found in element with unpaired electrons. Oxygen was

once thought to be diamagnetic, but a new revised molecular orbital (MO)

model confirmed oxygen’s paramagnetic nature.

An exception to the weak nature of diamagnetism occurs with the rather

large number of materials that become superconducting, something that

usually happens at lowered temperature. Superconducting, something that

usually happens at lowered temperatures. Superconductors are perfect

diamagnets and when placed in an external magnetic field expel the field line

from their interiors (depending on field intensity and temperature).

Superconductors also have zero electrical resistance, a consequence of their

diamagnetism. Superconducting structures have been known to tear

themselves apart with astonishing force in their attempt to escape an external

field. Superconducting magnets are the major component of most magnetic

response imaging system, perhaps the only important application of

diamagnetism.

A thin slice of pyrolitic graphite, which is an unusually strongly diamagnetic

material, can be stably floated on a magnetic field, such as that from rare

earth permanent magnets. This can be done with all components at room

temperature, making a visually effective demonstration of diamagnetism.

Diamagnetic materials have a relative magnetic permeability that is less than

1, and a magnetic susceptibility that is less than 0.


112

(a) Para magnetism:

Some materials exhibit a magnetization which is proportional to the

applied magnetic field in which the material is placed. These materials are

said to be paramagnetic.

Paramagnetism is the tendency of the atomic magnetic dipoles, due to

quantum – mechanical spin, in a material that is otherwise non – magnetic to

align with an external magnetic field. This alignment of the atomic dipoles with

the magnetic permeability greater than unity (or, equivalently, a small positive

magnetic susceptibility).

In pure Paramagnetism, the field acts on each atomic dipole

independently and there are no interactions between individual atomic

dipoles. Such paramagnetic behavior can also be observed in ferromagnetic

materials that are above their curie temperature.

Paramagnetic materials attract and repel like normal magnets when

subject to a magnetic field. Under relatively low magnetic field saturation

when the majority of the atomic dipoles are not aligned with the field,

paramagnetic materials exhibit magnetization according to curie’s law.

M = C (B / T)

Where , M is the resulting magnetization, B is the magnetic flux density

of the applied field, T is absolute temperature (Kelvin), C is a material specific

curie constant.

This law indicates that paramagnetic materials tend to become

increasingly magnetic as the applied magnetic field is increased, but less

magnetic as temperature is increased. Curie’s law is incomplete because it

fail to predict what will happen when most of the little magnets are aligned

(after everything is aligned, increasing the external field will not increase the

total magnetization) so curie’s constant really should be expressed as function

of how much of the material is already aligned.


113

Paramagnetic materials in magnetic fields will act like magnets but

when the field is removed, thermal motion will quickly disrupt the magnetic

alignment. In general paramagnetic effects are small (magnetic susceptibility

of the order of 10-3 to 10-5). Ferromagnetic materials above the Curie

temperature become paramagnetic.

(c) Ferromagnetism:

Ferromagnetism is phenomenon by which a material can exhibit a

spontaneous magnetization, and is one of the strongest forms of magnetism.

It is responsible for most of magnetic behavior encountered in everyday life,

and is the basis for all permanent magnets. These are a number of crystalline

materials hat exhibit ferromagnetism.

One can also make amorphous ferromagnetic metallic alloys by very

rapid quenching of liquid alloy. These have the advantage that their properties

are nearly isotropic. This results in low coercivitty, low hysteresis loss, high

permeability, and high electrical resistivity. A typical such material is a

transition metal – metalloid alloy, made from about 80% transition metal

(usually Fe, Co, or Ni) and a metalloid component ( B, C, SI, P, or Al) that

lowers the melting point.

(d) Antiferromagnetism:

In materials that exhibit Antiferromagnetism, the spins of magnetic

electrons align in a regular pattern with neighbouring spins pointing in

opposite directions. This is the opposite of ferromagnetism. Generally,

antiferromagnetic materials exhibit Antiferromagnetism at a low temperature,

and become disordered above a certain temperature. The transition

temperature is called the Neel temperature. Above the Neel temperature the

material is typically paramagnetic. The magnetic susceptibility of an

antiferromagnetic material will appear to go through a maximum as the

temperature is lowered; in contrast, that of a paramagnet will continually

increase with decreasing temperature. Antiferromagnetic materials have a

negative coupling between adjacent moment and low frustration.


114

Antiferromagnetic materials are relatively uncommon. An example is the

heavy – fermion superconductor URu2Si2

Magnetic susceptibility measurements:

The Vibration Sample Magnetometer (VSM), model 7304, Lake shore

Cryotronics, Inc., U.S.A., was used to characterize magnetic properties of the

metal chelates. The Model 7304 is capable of characterizing a verity of

particulate and continuous magnetic media materials including; audio, video

and digital data tapes, flexible media, magneto – optical materials, sputtered

and plated thin film materials including multilayer GMR,CMR, exchange- bias

and spin valve materials. In addition to standard major and minor hysteresis

loop measurements, the lake shore Model 7304 also measure remanence

curves, and facilities investigation of anisotropic materials with a vector option.

Permanent magnet materials including rare – earth magnets (NdFeB, SmCo,

etc), polymer – bonded magnets, electrical steel, iron oxides (ferrites) etc. are

also readily characterized in Model 7304. In addition to all full loop properties,

2nd quadrant characteristics may be measured, energy products determined.

Curie point determinations with an optional furnace are also possible. The

Model 7304 is also ideally suited for basic measurements over a broad range

of magnetic fields and temperatures employing optional cryostats and liquids

are all readily accommodated. Materials that may be characterized include;

multilayer films, high and low temperature superconductors, molecular

magnets, rare –earth and transition metal materials, spinglsses, amorphous

magnets, and more. It measures the magnetic moment of any magnetic

material in any form, from 5 x 10-6 emu to 1 x 103 emu. A description and

theory are as follows:

When a sample material is placed in a uniform magnetic field, a dipole

moment proportional to the product of the sample susceptibility times the

applied field is induced in the sample. A sample undergoing sinusoidal motion

as well induced an electrical signal in suitable located stationary pick up coils.

This signal, which is at the vibration frequency, is proportional to the magnetic

moment, vibration amplitude, and vibration frequency. The material under


115

study is contained in a sample holder, which is centered in the region between

the pole pieces of magnet. A slender vertical sample rod connects the sample

holder with a transducer assembly located above the magnet, which supports

the transducer assembly with sturdy, adjustable supports rods. The

transducer converts a sinusoidal AC drive signal, provided by a circuit located

in the console, into a sinusoidal vertical of the sample rod and the sample is

thus made to undergo a sinusoidal motion in a uniform magnetic field. Coil

mounted on the pole pieces of the magnet pick up the signal resulting from

the sample motion. This AC signal at the vibration frequency is proportional to

the magnitude of the moment induced in the sample. However, it is also

proportional to the vibration amplitude and frequency. The constancy

maintained in the drive amplitude and frequency is so that the output

accurately tracks the moment level without degradation due to variation in the

amplitude and frequency of vibration.

This technique depends on being able to use a vibrating capacitor

located beneath the transducer to generate an AC control signal that varies

solely with the vibration amplitude and frequency. The signal, which is at the

vibration frequency, is fed back to the oscillator where it functions as the

reference drive signal. The signal from the sample is developed in the pickup

coils, then buffered, amplified, and applied to the demodulator. There it is

synchronously demodulated with respect to the reference signal derived from

the moving capacitor assembly. The resulting DC output is an analog of the

moment magnitude alone, uninfluenced by vibration amplitude change and

frequency drift.

The moment calibration of Vibrating Sample Magnetometer is

traditionally performed with a nickel standard at an applied field above the

saturation field of nickel, normally 5000Oe. Lake shore supplies a nickel

cylinder of 99.99 % purity, an aspect ratio of nearly 1: 1 and a mass of

approximately 0.02 grams. These samples are etched and weighted prior to

measuring their saturation magnetization. The saturation magnetization of the

nickel sample is measured with a VSM calibrated with a NIST (NBS) nickel


116

standard. There fore, calibration on a single range ensures the overall

calibration of the electronics.

Lake shore performs moment- offset calibration. Additional moment

offset adjustments should not be required, but lake shore allows for software

offset correction to the moment readings. Lake shore calibrates both the gain

and the offset of the measurement / control loop to specification accuracy

during final assembly and testing.

The VSM report the total magnetic moment, m, of a sample in emu.

However, the end gole of the magnetic measurement is not the moment in

emu, but to get the effective magnetic moment, µ eff. Therefore, the VSM

magnetic moment can be converted to susceptibility of a sample has units of

volume and is defined for paramagnetic materials by the equation:

χ (cm3) = m (emu)/ H (Oersted).

The gram susceptibility, χ g was calculated using the expression:

Gram susceptibility: χ g = χ (cm3)/mass

The gram susceptibility was multiplied by the molecular weight of the

sample to obtain molar susceptibility, χ m. . A correction was applied for the

diamagnetism of the ligands to get the correction molar susceptibility χ m’. The

effective magnetic moment µ eff was calculated from the expression:

µ eff. = 2.84 (χ m’ x T) 1/2

Where T = absolute temperature (K)

Magnetic susceptibility of the copper (II) Schiff base chelates.

The Cu (II) ion has [Ar] 3d9 electronic configuration and its compounds

are expected to have magnetic moment close to be spin – only value

1.73B.M. This ion has one unpaired electron whatever the geometry

octahedral, plane or tetrahedral.


117

The single-ion magnetic properties of copper (II) are fairly

straightforward. Spin – orbit coupling is large, causing the g values to lie in the

range 2.0 to 2.3, but because copper has an electronic spin of only ½, there is

no zero – field splitting effects. The g values are often slightly anisotropic,

being for example 2.223(║) and 2.051 (┴) in Cu (NH3) SO4 .H2O.The one

problem that dose arise with this ion is that it rarely occupied a site of high

symmetry; in octahedral complexes ,two trans ligands are frequently found

substantially further from the metal than the remaining four. This has led to

many investigation of copper as the Jahn – Teller susceptible ion, per

excellence. Dynamic Jahn - teller effects have also been frequently reported

in EPR investigations of copper compounds at low temperatures. Tetrahedral

copper is also well-known, through it usually quite distorted because of the

Jahn – Teller effect. It is found, for example, in Cs2CuCl4, a system with an

average g-value of 2.20.

The magnetic moment of Cu (II) ion in octahedral or planar

stereochemistry generally lies around 1.98 B.M. at room temperature. In

absence of magnetic exchange between neighbouring copper ions, Curie’s

law is obeyed. For tetragonal coordinated Cu (II) ion with 2T2g ground term, the

anticipated magnetic moment is 2.2B.M. At room temperature, some literature

magnetic moment data of the Cu (II) complexes are summarized as following

table 5.1.


118

Table – 5.1 Literature magnetic moment data of the Cu (II) complexes

No. Complexes µ eff. (B.M.) Geometry Reference

1 [Cu(L’)(NO3)2] 1.80 Tetrahedral 15

2 [Cu(L’)2] 1.99 Square

planer 16

3 [Cu(Sal)2acphen]H2O 1.71 Octahedral 17

4 [Cu(5-Clsal)((bzal)] 2.18 Tetrahedral 14

5 [CuL2](ClO4)2H2O 1.55 Tetrahedral 8

6 [Cu(SB-Cl)2benen] 1.89 Octahedral 18

Where L’ = 1.1’-diacetyl ferrocene,

L’ = Salicylidene –p- aminoazobenzene,

acphen = bis (acetophenone) ethylenediamine,

5-Clasal = 5 –chlorosalicyldehyde,

bzal = 1 – phenyl- 1, 3 – butanedione,

L2 = 2 – (thiomethyl – 2’ – benzimidazolyl) benzaimidazole,

SB-Cl = chlorosalicylidene – p anisidene,

benen = bis (benzylidene) ethelenediamine,


119

In presence case the magnetic susceptibility of the Cu (II) chelates are

given in table 5.2, the magnetic moment value of the Cu (II) chelates lies in

between 1.79 – 1.95 B.M. these values are close to the spin allowed values

expected for a S = ½ system (1.73 B.M.) and may be indicative of an

octahedral geometry around the Cu (II) ions 10

The representative plot of field Vs moment of the metal chelate are

given on page no.121.

Table 5.2 Magnetic susceptibility of copper (II) Schiff base chelates

Schiff base Cu(II) chelates µ eff.(B.M.)

Cu(II)( L1-o-v-A)2H2O 1.95

Cu(II)( L2 - Sal – A)2H2O 1.87

Cu(II)(L3 -O-H-Naph.-A) 2H2O 1.79

Where

L1 –o-v-A = 6,6’-(4,4’-(cyclohexane-1,1-diyl) bis(4,1-phenylene)) bis (azan-1-yl-1- ylidene) bis (methan-1-yl-1ylidene) bis (2-methoxy phenol)

L2-sal- A = 2,2’-(4,4’-(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene) diphenol

L3-O-H-Naph.- A =1,1’-(4,4’(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol


120

Calculation of the effective magnetic moment value from the graph for

the [Cu(II)( L1-o-v-A)2H2O]

χ m = slop at HC x mol.wt.

Mass

= 1.76 x 10 -7 x 632.17

0.070

= 1.589 x10-3

µ eff. = 2.84 √ χ m x T where T = absolute temperature (298oK)

µ eff. = 2.84 √1.589 x10-3 x 298

µ eff. = 1.95 B.M.


121

Fig. 5.1 Plot of field Vs moment of the [Cu(II)( L1-o-v-A)2H2O]

Slop at HC 1.76 e-07 amu slop: 0 amu/Oe


122

Magnetic susceptibility of the cobalt (II) Schiff base chelates.

The Co (II) ion has 3d7 configurations with free ion ground term 4F in

high – spin complexes, and 2G in low – spin complexes. So it has three

unpaired electrons in it sub shell. The observed value of magnetic moment is

higher than calculated on the basis of spin – only formula µ = 4S(S+1). A

value is 3.87 B.M. to expect to be exhibit magnetic moment is equal to spin –

only values.

This suggests that there is also an orbital contribution. To have an

orbital angular moment it must be possible to transform an orbital into an

equivalent orbital by rotation. It is possible to transform the t2g orbitals (dxy, dxz,

and dyz) into each other by rotating 900 . It is not possible to transform the e.g.

orbital’s in this way (e.g. the dx2-y2 into the dz2 ), since they have different

shapes. If the t2g orbital are all singly occupied, then it is not possible to

transform the dxy into dxz or dxz since they already contain an electron with the

same spin. Similarly it is not possible to transform the t2g orbitals if they are all

doubly occupied. Thus configuration with (t2g)3 or (t2g)0 have no orbital

contribution, but the other all have an orbital contribution. Thus in octahedral

complexes the following arrangements have an orbital contribution:

(t2g)1 (eg)0 (t2g)2(eg)0 (t2g)4(eg)2 (t2g)5(eg)2

Co2+ has the (t2g)5 (eg)2 configuration ,hence the high value of µ is due to the

orbital contribution. Some literature magnetic moment data of the Co (II)

complexes are summarized as following table 5.3.


123

Table - 5.3 Some literature magnetic moment data of the Co (II)

complexes are summarized as follow.

No. complexes

µ eff

(B.M.) Geometry Reference

1 [Co(H2L)(H2O)3] 5.40 Octahedral 4

2 [Co(Py)4(SO3Cl)2] 5.11 Octahedral 2

3 [CoL2Cl2] 5.75 Octahedral 5

4 Co(CNCHMe)4{NH2CSNH2}](ClO4)2 4.92 Octahedral 6

5 [Co(LH2)] 4.62 Octahedral 3

6 [CoL’Cl2] 4.42 Octahedral 7

7 [CoL”Br2] 4.90 Octahedral 8

8 Co2L’2X2 4.40 Tetrahedral 19

9 Co(L3)2 3.85 Tetrahedral 20

Where

H2L = salicylidine – 2 – aminobenzimidazole

Py = pyridine

L = 2- (1-indazolyl)benzothizole

LH = α – bromo acetoacetanilide semicarbazone

L’ = 1,4,8,12- tetraaza – 4 – (1’,1’ – dimethylethyl ) – 2

(1’’,1’’,2’’,2’’,3’’,3’’,3’’-heptafluoropropyl)-9,11-(dimethylcyclotetradeca)-

1,4,8,11-tetraene

L’’ = 2- (thiomethyl-2-benzimidazolyl)benzimidazole)

L’2 =4-[2’-hydroxysalicylidene5’ (2’’thiozlyazo)] chlorobenzene

X2 = Cl

L3 = p- aminoacetophenoneoxime – 5 - hydroxysalicylaldiminato


124

In present work the magnetic moment values of Co (II) Schiff base

chelates are presented in table 5.4. The magnetic moment values for the Co

(II) chelates have been used as criteria to determine the type of coordination

around the metal ion. Due to the intrinsic orbital angular momentum in the

ground state, there is consistently a considerable orbital contribution and the

effective magnetic moment values of the Co (II) chelates are lies in between

3.90 - 4.10 B.M., which are slightly greater than the spin – only value

(3.87B.M.). This high value of the magnetic moment and the stoichiometries

suggest a coordination number of six for the central Co (II) ion and an

octahedral geometry 11. The representative plot of field Vs moment of the

metal chelate are given on page no.126.

Table - 5.4 Magnetic Susceptibility of the cobalt (II) Schiff base Chelates.

Schiff base metal chelates µeff . (B.M.)

Co(II)( L1-o-v-A)2H2O 3.98

Co(II)(L2 -Sal –A)2H2O 3.90

Co (II)( L3 -O-H-Naph.-A) 2H2O 4.10

Where

L1 –o-v-A = 6,6’-(4,4’-(cyclohexane-1,1-diyl) bis(4,1-phenylene)) bis (azan-1-yl-1-

ylidene) bis (methan-1-yl-1ylidene) bis (2-methoxy phenol)


L3-OHNaph.- A =1,1’-(4,4’(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol


125


the [CoL1-o-V –A-2H2O]

χ m = slop at HC x mol.wt. Mass

= 4.74 x 10 -7 x 627.56

0.045

= 6.610 x 10 -3

µ eff. = 2.84 √ χ m x T where T = absolute temperature (298oK)

µ eff. = 2.84 √ 6.610X10-3 x 298

µ eff. = 3.98 B.M.


126

Fig. 5.2 Plot of field Vs moment of the [CoL1-o-V –A-2H2O]


127

Magnetic susceptibility of the Nickel (II) Schiff base chelates.

The electronic configuration of Ni (II) is [Ar]3d8. Ni (II) forms stable chelates with coordination number four and six. Compounds of higher coordination number are rare. The principal geometries of its complexes are octahedral and square – planar. Some trigonal bipyramidal, square pyramidal and tetrahedral complexes are also known.

In tetrahedral ligand field Ni (II) has an orbitally degenerate 3T1g(P) term which will give rise to a relatively large orbital contribution. In regular tetrahedral stereochemistry magnetic moment is observed to be around at 3.5 to 4.0 B.M. The diamagnetic four coordinated complexes are square planar. In octahedral stereochemistry the magnetic moment of the Ni(II) complex is found to have value in between 2.8 to 4.1 B.M., consideration of spin-orbit coupling and contribution from 3A2g and the next higher 3T2g states give a some what higher magnetic moment than spin – only value 2.83 B.M. for the stereochemistry of the Ni(II) complexes, the magnetic data are specially significant. Since the stereochemistry of the attached Schiff base ligand affects the quenching of orbital magnetism, the size of the latter may in suitable cases be used as a guide to stereochemistry.

Table - 5.5 Some literature magnetic moment data of the Ni(II) complexes

are summarized as follow.

No. Complexes µ eff

(B.M.) Geometry References

1 [NiL2Cl2] 2.99 Octahedral 5

2 [NiL]Cl2 3.06 Octahedral 9

3 Ni(HL)2H2O 3.85 Octahedral 4

4 [Ni(L)2] 2.40 Octahedral 12

5 [NiHL(H2O)Cl] 2.87 Octahedral 13

6 Ni(5-ClSal)(acac)(H2O)2 2.73 Octahedral 14

7 Ni(L1)2 2.71 Tetrahedral 19


128

Where

L = 2(1- indazolyl)benzothizole,

L = 6, 10, 16, 20- tetraketo- 8, 18 – dithia – 1, 5, 11, 15-

tetrazocycloeicosane,

L = salicylidine -2- aminobenzimidazole,

L = 4- (1-phenyl – 1- methylcyclobutane -3-yl)-2-(2-hydroxy-5-

bromo)benzalidene aminothiazide

L= 1,4-di(hydroxybenzylidene)thio – semicarbazide

5-Clsal = 5-chlorosalicylaldehyde

acac = acetylacetone

L = salicylidene -1- amino -5- benzoyl -4- phenyl -1H –pyrimidine-2-

thione

L1= p- aminoacetophenoneoxime – 5 - hydroxysalicylaldiminato

Magnetic susceptibility of the Ni (II) Schiff base metal chelates in the

present work have been measured at room temperature. The values of

magnetic moment are incorporated in Table 5.6. The magnetic moment

values are observed in the range 2.81 to 3.11 B.M., corresponding to 2-

unpaired electron. The magnitude of magnetic moment clearly indicates that

Ni (II) ion has paramagnetic nature in all the Ni (II) Schiff base metal chelates,

with octahedral structure. The slight variation in magnetic moment values for a

high-spin Ni+2 chelates depend on the magnitude of the orbital contributions,

expected for similar hexa – coordinated Ni (II) ions.21 The representative plot

of field Vs moment of the metal chelate are given on page no.131.


129

Table - 5.6 Magnetic susceptibility of the Nickel (II) Schiff base chelates.

Schiff base metal chelates µeff . (B.M.)

Ni(L1-o-v- A) (H2O)2 2.94

Ni(L2-sal- A) (H2O)2 2.81

Ni(L3-O-H-Naph.- A) (H2O)2 3.11

Where

L1 –o-v-A = 6,6’-(4,4’-(cyclohexane-1,1-diyl) bis(4,1-phenylene)) bis (azan-1-yl-1- ylidene) bis (methan-1-yl-1ylidene) bis (2-methoxy phenol)


L3-O-H-Naph.- A =1,1’-(4,4’(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol


130


the [Ni (L1-o-vA)

χ m = Slope at HC x mol.wt. Mass χ m = 3.16 x 10 -7 x 627.34

0.055

χ m = 3.6033 x 10-3

µ eff. = 2.84 √ χ m x T where T = absolute temperature (298o K)

µ eff. = 2.84 √ 3.6033 x 10-3 x 298

µ eff. = 2.94 B.M.


131

Fig. 5.3 Plot of field Vs moment of the [Ni (L1-o-vAH2)


132

Magnetic susceptibility of the Zinc (II) Schiff’s bases chelates.

In Zn (II) d sub shell is completely filled there are no unpaired electrons, hence the compounds of Zn (II) metal chelates are expected to be diamagnetic. Most of the Zn (II) metal chelates are expected to tetrahedral. However, octahedral Zn (II) metal complexes are reported.22

In present work, the magnetic moment determination of the Zn (II) metal chelates shows diamagnetic nature. Therefore, they have no unpaired d- electron in Zn (II), hence the chelates must be diamagnetic. The chelates are yellowish colour, which is also indicating the absence of unpaired electrons. The structure may be tetrahedral or octahedral.


133

References:

1. Figgish B.N., Introduction to ligand fields. The magnetic properties of complex ions; interscience Publishers. John Wiley and sons: new York, 248, (1967).

2. Siddiqi, Z. A.; Shakir, M.; Aslam, M.; Khan, T.A.; Zaidi, S. A. A. Synth. React. Inorg. Met.-Org. Chem.13 (4), 397, (1983).

3. Deepa K.; Arvindakshan K.K. Synth. React. Inorg. Met.-Org. Chem.31

(3).429, (2004).

4. Mohamed G.G; Abd EL – Wahab,Z.H. Jou. Of Therm. Ana. And Colri.73, 347 (2003).

5. Khan T.A.; Shahjahan, Synth. React. Inorg. Met.-Org. Chem. 31(6), 1023, (2001).

6. Becker C.A.; Odisitse S. Synth. React. Inorg. Met.-Org. Chem.30 (8), 1547, (2000).

7. Shakir M.; Chingsubam P.;Azim Y.;Parveen S.; Synth. React. Inorg. Met.-Org. Chem. 34 (5), 847, (2004).

8. Satyanarayana S.; Synth. React. Inorg. Met.-Org. Chem. 34 (5), 883, (2004).

9. Chandra S.; Gupta N.; Gupta L.K.; Synth. React. Inorg. Met.-Org. Chem. 34(5), 919,(2004).

10. Speca A. N.: Karayannis M.: Pyleuski L.L. J.Inorg.Nucl.Chem. 35, 3113 (1973).

11. Patel M.M.; Malavanan R. J. Macromol. Sci. Chem. 19A ,951 (1983).

12. Yilmaz I.: Cukurovali A.: Ahmedzale M., Synth.React.Inorg.Met.-Org.Chem. 30 (5), 919 (2000).

13. Mashaly M. M.; Abd-EL Wahab Z. A. Synth.React.Inorg.Met.-Org.Chem. 34 (2), 233 (2004).

14. Prasad R.N.; George R. Synth.React.Inorg.Met.-Org.Chem. 34 (5), 943 (2004).

15. Chohan Z. H. Synth.React.Inorg.Met.-Org.Chem. 34 (5), 833 (2004).


134

16. Ragiumov A. V. Mamedov B.A. Polymer 60, 1851 (1989).

17. Patel B.K.; Patel M.M. Ind. J. of Chem. 29(1), 90 (1990).

18. Patel M. N.; Patel K. N.; Patel N. H. Synth.React.Inorg.Met.-Org.Chem. 32 (10), 1879 (2002).

19. L.V.Gavali; P.P.Hankarep J. of Physical Science.11, 147, (2007).

20. Erdal Canpolat, Mehmet KAYA; Turk J. Chem. 29, 409, (2005).

21. Issa Y. M.; El- Hawary W. F.; Abdel –Salam H. A. Transition Met. Chem. 20, 423 (1995).

22. Aswar A. S.; Mahale R. G.; Kakede P.R.; Bhadange S. G. J.Ind. Chem. Soc. 75, 395 (1998).

23. J.D.Lee; “Concise inorganic chemistry” 5th edition john Wiley ,2003


135

GENERAL DISCUSSION

Schiff base ligands :-

The large number of Schiff bases is forming metal complexes. We have

synthesized three new Schiff bases of 1, 1’ bis (4- aminophenyl) cyclohexene [A]

like

(1). 6, 6’-(4, 4’-(cyclohexane-1, 1-diyl) bis (4, 1-phenylene)) bis (azan-1-yl-1-

ylidene) bis (methan-1-yl-1ylidene) bis (2-methoxy phenol) (L1-o-v-AH2)

(2). 2, 2’-(4, 4’- (cyclohexane-1, 1-diyl) bis (4, 1-phenylene)) bis (azan-1-yl-1-

ylidene) bis (methan-1-yl-1-ylidene) diphenol (L2 - Sal – AH2)

(3) 1,1’-(4,4’(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(azan-1-yl-1-ylidene)bis

(methan-1-yl-1-ylidene) dinaphthalen-2-ol (L3 -O-H-Naph.-AH2)

They are different in colors; dissolve in almost all organic solvent, like

benzene, CCl4, CHCl3. Their characteristic properties are discussed in chapter-3.

These Schiff base ligands have reactive system containing hydroxyl group (OH)

and azomethine group (C═ N). Thus, they are good chelating agent or ligands.

We have synthesized metal complexes of Cu (II), Ni (II), Co (II) and Zn (II) with

these ligands.

On the basis of synthesis elemental analysis, spectral studies. The

general structure of the ligands proposed to represented as,

NN

HC

OH HO

CH

OCH3 H3CO

L1-o-v-AH2


136

N NHC

OH HO

CH

L2 - Sal – AH2

NN

HC

OH HO

CH

L3 -O-H-Naph. – AH2


137

The elemental analysis as prescribed in chapter -3 table 3.1 on page.43

agrees with theoretical expected value. Thus supporting the suggested molecular

formula.

Absorption spectral studies of Schiff bases.(UV/VIS.):-

In general as it is known that the absorption of light energy by

organic compounds in visible and ultraviolet region involves transition of

electrons from the ground state to higher states. The electronic transitions that

are involved in the ultraviolet and visible regions are of the following types.

σ→ σ* , n→ σ*, n→π* , π → π*

The absorption spectra of Schiff base ligands in UV& Visible region show

bands at 280-330nm, 270-350nm, and 264 -465nm. These are attributed to π →

π* and n → π* transaction of phenyl ring and azomethine respectively. The slight

shift in the λ max due to change in molecular weight of the ligands

Table- 6.1

Absorption maximum (λ max.) and (log e) of the Schiff’s bases.

Sr. No.

Name of Schiff’s bases λ max[nm]

1 L1 -O-V-AH2 326

282

2 L2 -SAL-AH2 346

273

3 L3 – O-Naph.- AH2

464.50

444.00

264.00


138

IR Spectral studies of Schiff base ligands :-

The IR spectra of all the ligands are on page no. 47-49 in chapter -3, are

identical with slight variation in group frequency as shown in table 6.2 on

page139 , which are according to the suggested structure of the all ligands

molecules.


139

Table – 6.2

IR Spectral Data of Schiff bases (cm-1)

Schiff bases ligands

Hydroxyl-OH

(H2O)

Alkane -CH2 Aromatic

Schiff’s base

O-H str. O-H def.

C-H str. (asym.)

C-H str. (sym.)

C-H def. (asym.)

C-H def. (sym.)

C-H str.

C=C

C-H ( I.p.d

C-C (o. O .p. d. )

CH=N str.

C-N def.

L1 -O-V-AH2

3451

1407.7

2925.9

2869.1

1454.7

1396

3060

1572.3

1114.5

830

1626.7

1277.7

L2 -SAL-AH2

3450.3

1406.3

2936.0

2865.7

1463.8

1365.0

3068.5

1509.6

1082.5

828.4

1615.7

1255.7

L3–O-Naph.-AH2

3426.9

1326.1

2930.7

2864.5

1498.9

1246.2

3041.0

1571.5

1085.1

822.8

1621.0

1173.7

NMR spectral studies of Schiff base ligands:-

The NMR spectral bands are presented on page 50-52 and their value is

presented in table 3.7- 3.9 in chapter-3 on page 50-52. The structure of the

Schiff base ligands molecule is further supported by the NMR spectral data.

Mass spectral studies of Schiff base ligands:-

For purpose of supporting the proposed structure of the Schiff bases. The

mass spectral analysis was carried out. The mass spectra are presented on page

53-55 in chapter-3. These data are also in good agreement with proposed

structure of Schiff base ligands molecules.

Metal chelates:-

Metal complexes of Cu (II), Ni (II), Co (II), and Zn (II) were synthesized

and the studies of their characteristic, properties are mentioned in chapter - 3.

All the copper (II), nickel (II), cobalt (II), and Zn (II) complexes are

insoluble in water and common organic solvents. It is soluble in DMSO and DMF.

From the elemental analysis it is found that the all complexes are type ML.

The molecular weight determine by Rast’s camphor method although not

very reliable still it is in agreement with the suggested molecular formula of all

complexes.

The conductivity of solution of all complexes in DMF was measured and

low values of conductivity observed suggest that the metal complexes are non –

ionic in nature.

Infrared spectra

Infrared spectroscopy deals with the study of molecular vibrations and

rotations. One of the important applications of vibrational spectra is the


141

determination of shape of a molecule. Although the infrared spectrum is

characteristic of the entire molecule, it turns out that certain functional groups

give bands at or near the same frequency regardless of the structure of the rest

of molecule. This fact forms the basis of the use of infrared spectra in qualitative

identification of a substance. The spectra of all metal complexes are given in

chapter -3. Discussion is as following.

The infrared spectra of Cu (II) chelates

The copper (II) complexes exhibit a broad band in the region 3400-3000

cm-1, suggesting the presence of coordinated water molecules1. The weak band

around 850 cm-1 are assigned as υ (OH) stretching rocking and wagging

vibration2. The IR spectra of Schiff bases display a strong absorption bands at

1615.7, 1626.7 and 1621.0 cm-1 for L1-o-v-AH2, L2 - Sal – AH2 and L3 -O-H-

Naph.-AH2 respectively assignable to C= N stretching mode, shift towards lower

frequency region by 1607.5, 1610.5, 1612.0 respectively in the complexes

indicating coordination through the azomethine nitrogen.3,4. The appearance of

sharp bands around 1441.7 cm-1, 1444.7, cm-1 and 1321.6 cm-1. Is attributed to υ

(C-O) band, which indirectly supports bonding of phenolic oxygen to metal ion.

The band observed in the region of 521-551cm-1 is attributed to υ (M-N). The υ

(M-O) band may be observed in the region 475-495 cm-1 5, 6. The IR spectra are

represented as in fig.3.13 – 3.15 on page no.63-65. In chapter-3

The infrared spectra of Ni (II) chelates

The nickel (II) complexes exhibit a broad band in the region 3400-

3425cm-1, suggesting the presence of coordinated water molecules 1. the weak

band around 856 cm-1 are assigned as υ (OH) stretching rocking and wagging

vibration 2 The IR spectra of Schiff bases display a strong absorption bands at




142


indicating coordination through the azomethine nitrogen to the metal.7 The

appearance of sharp bands around 1440.7 cm-1, 1444.5, cm-1 and 1327.1cm-1. Is

attributed to υ (C-O) band, which indirectly supports bonding of phenolic oxygen

to metal ion 8. In the low frequency region, the band observed in the region of

520-547cm-1 is attributed to υ (M-N). In the region of 470-490 cm-1 attributed to

υ (M-O) phenolic band 6. The IR spectra are represented as in fig. 3.17 - 3.19.On

page no.72-74, in chapter - 3

The infrared spectra of Co (II) chelates

The cobalt (II) complexes exhibit a broad band in the region 3400-

3429cm-1, suggesting the presence of coordinated water molecules9. the weak

band around 855 cm-1 are assigned as υ (OH) stretching rocking and wagging

vibration 2 .The IR spectra of Schiff bases display a strong absorption bands at




indicating coordination through the azomethine nitrogen to the metal.7 The

appearance of sharp bands around 1445.5 cm-1, 1436.0, cm-1 and 1329.0cm-1. Is

attributed to υ (C-O) band, which indirectly supports bonding of phenolic oxygen

to metal ion 8. In the low frequency region, the band observed in the region of

500-515cm-1 is attributed to υ (M-N). In the region of 475-485 cm-1 to υ (M-O)

phenolic band may be observed 6, 7. The sharp band near 725-760cm-1 and

1490-1530cm-1 are due to aromatic υ (C-H) 10. And υ (C=C) 11, respectively. The

IR spectra are represented as in fig.3.21 – 3.23 on pages no.81 -83, in chapter- 3


143

The infrared spectra of Zn (II) chelates

The zinc (II) complexes exhibit a broad band in the region 3400- 3410cm-1,

suggesting the presence of coordinated water molecules 8. the weak band

around 847 cm-1 are assigned as υ (OH) stretching rocking and wagging vibration

2 .The IR spectra of Schiff bases display a strong absorption bands at 1615.7,

1626.7 and 1621.0 cm-1 for L1-o-v-AH2, L2 - Sal – AH2 and L3 -O-H-Naph.-AH2

respectively assignable to C= N stretching mode, shift towards lower frequency

region by 1614.3, 1610.2, 1611.0 respectively in the complexes indicating

coordination through the azomethine nitrogen to the metal.7 The appearance of

sharp bands around 1459.3 cm-1, 1453.9, cm-1 and 1392.0cm-1.Is attributed to υ

(C-O) band, which indirectly supports bonding of phenolic oxygen to metal ion8.

In the low frequency region, the band observed in the region of 500-575cm-1 is

attributed to υ (M-N). In the region of 450-470 cm-1 to υ (M-O) phenolic band

may be observed 5, 6 the sharp band near 725-760cm-1 and 1490-1530cm-1 are

due to aromatic υ (C-H) 10. and υ (C=C)11,respectively. The IR spectra are

represented as in fig. 3.25 -3.27 on pages 90 – 92, in chapter - 3

Thermo gravimetric analyses

Thermogravimetric analysis has been obtained by a model PerkinElmer

Pyris1 TGA instrument. The thermal curves were obtained at a heating rate of

100C/ min over the temperature range of 50-8000C. It has been observed that all

the metal chelates clearly show a weight loss corresponding to two water

molecules in range ~110-2950C, indicating that these water molecules are

coordinating to the metal ion. 12-16. The TG curves indicate that in the

temperature range between ~ 295 -700 0C and 8000C the Schiff base molecules

are lost. In all the cases the final products are metal oxides. These results are in

good accordance with the composition of the metal chelates. The result are given

in table 4.1 on page 102 and selected thermogram of metal chelates are given in

fig.4.1 – 4.4 on page 103-106 in chapter -4.


144

Magnetic properties and Electronic spectra of Cu(II) chelates

The magnetic moment of Cu (II) ion in octahedral or planar

stereochemistry generally lies around 1.98 B.M. at room temperature. The

magnetic susceptibility of copper (II) complexes is given in table 5.2 in chapter -

5.These magnetic moment values are lies between 1.79 to 1.95 B.M. are very

closed to spin- only value (1.73B.M.). These values consistent with an octahedral

geometry. 17. Most of Cu (II) complexes and compounds have a distorted

octahedral structure and are blue or green. The metal ion has the d9 electronic

configuration gives rise to the 2D free ion term, which is split in a regular

octahedral field into a lower doublet Eg level and an upper triplet T2g level.18,19.

Thus , only one spin allowed d-d transition 2Eg → 2T2g the d9 configuration is

highly Jahn – Teller unstable and the resulting

tetragonal distortion(D4h) leads to the further splitting of Eg and T2g level into B1g

,A1g, and B2g ,Eg. Levels, respectively 20-24

, this splitting of the state increases with

the tetragonal component of the crystal field. As the energy of the 2A1g state

increases, a situation may arise in which this is sufficient close to the 2Eg and

2B2g

The UV/Visible absorption spectra of all the copper (II) chelates are shown

in fig. 3.12 in chapter -3 and spectral data are summarized in table 3.11 in

chapter-3. All the Cu (II) chelates show π→ π*, n→π* and C→T, transition at

220-255, 270-305, and 300-400 respectively and- d → d transition at

597,727,411 nm for all complexes. This assignment is in agreement with the

general observation 25. According absorption spectra and magnetic

susceptibility value, geometry of Cu(II) Schiff base metal complexes are conform

the distorted octahedral


145

Magnetic properties and Electronic spectra of Ni (II) chelates

Ni (II) is 3d8 has two unpaired electron on its subshell. Hence, it is

assumed that all compounds containing Ni (II) are expected to exhibit magnetic

moment close to spin- only values for two unpaired electrons (2.83 B.M.).

Deviation from the spin –only value of 2.83 B.M., i.e. the orbital contributions to

the magnetic moment, depends on the stereochemistry of the complex. In some

cases the magnetic moments indicate the exact stereochemistry of the complex.

For example the Ni(II) complexes 26,27 exhibit zero magnetic moment and are

considered to have diamagnetic behavior, while those Ni(II) complexes 28 having

magnetic moments 2.8-3.3 B.M. may exist in octahedral stereochemistry. The

excess values may be due to distorted nature. The room temperature magnetic

moments for tetrahedral Ni (II) complexes 29 usually lie in the range 3.6 -4.1 B.M.

The magnetic moments of the Ni (II) complexes studied in present work

are given in table 5.6 in chapter -5.These magnetic moment of the Ni (II)

complexes were found to be in the range 2.81 to 3.11 B.M. corresponding to two

unpaired electrons. The magnitude of magnetic moment clearly indicates that Ni

(II) ion has paramagnetic nature in all the complexes, with octahedral structures.

The slightly higher magnetic moment in some of the cases may be assigned due

to orbital contribution. The magnetic moment values in present work are within

range expected for similar hexa-coordinated Ni (II) ions, which is also supported

by many similar observation30-31.

The large numbers of sterochemical forms in nickel (II) complexes are

reported. Different types of d-d transition in various sterochemical forms of Ni (II)

are briefly discussed.

The absorption spectra of six-coordinated nickel (II) complexes have been

studied extensively32. It shows simple spectra involving three main bands in the

regions 7,000- 13,000; 14,000-17,000 and 20,000 – 27,000 cm-1. The bands may

be assigned to 3A2g → 3T2g (F), 3A2g →

3T1g (F), 3A2g →

3T1g (P)

respectively33. Sometime, second transition exhibits double peak nature, for

which different explanation are suggested 34, 35.


146

The tetrahedral nickel (II) complexes have a multiple band at 15,000 -

18,000cm-1 which is assigned to 3 T1 (F) → 3 T2 (P) (v3) transition. Weak band on

either side are spin- forbidden transitions assigned to components of 1D and 1G

level respectively 36.

The square planar complexes of nickel (II) are usually orange, red, brown,

or yellow but purple and green coloured examples are also known 37-40. The

majority of these complexes exhibit a strong absorption band in the visible region

between 15,000 and 25,000 cm-1 may be assigned to 1A1g → 1A2g transition and

in many cases a second more intense band between 23,000 and 30,000cm-1

assigned to the 1A1g → 1B1g transition 35, 38. Square planar complexes of nickel

(II) can readily be distinguished from octahedral or tetrahedral complexes by

absence of transition below 10,000 cm-1.

The electronic absorption spectra of Ni (II) chelates are shown in fig .3.16

in chapter -3 and spectral data are summarized in table 3.14 in chapter -3. All the

Ni (II) chelates shows π→ π*, n→π* and C→T, transition at 250-260, 270-300,

and 300-325 and d-d transition at 326-405 and at 759. Using energy level

diagram, this three band may be assigned to 3A2g → 3T2g (F), 3A2g →

3T1g

(F), 3A2g → 3T1g (P) respectively, for an octahedral stereochemistry 41 .

Magnetic properties and Electronic spectra of Co(II) chelates

The Co (II) ion has 3d7 configurations with free ion ground term 4F in high-

spin complexes, and 2G in low-spin complexes. Octahedral and tetrahedral

stereo chemistries are very common for the Co (II) 42. Square planar 43 and

pentacoordinated 44 complexes of Co (II) are also reported. Tetrahedral

complexes are usually more favourable for Co (II) than any other transition metal

ion because the ligand field stabilization favours the tetrahedral stereochemistry

relative to octahedral one.

The magnetic properties of high-spin octahedral cobalt (II) complexes are

governed by orbital degenerated ground term 4 T1g, this provide the orbital


147

contribution to the magnetic moment, so that at room temperature magnetic

moment values are found to lie in the range of 4.30-5.20 B.M. and these values

very appreciably with change in the temperature 45. Low –spin octahedral Co (II)

complexes have 2Eg ground term arising from the t2g6 eg

1 electronic configuration

46. The magnetic moment values of these types of complexes usually lie in the

range 1.70 – 1.85 B.M.

In present work magnetic moment values of all the complexes are

presented in table 5.4 in chapter 5. The magnetic moment of the Co (II)

complexes were found to be in the ranges 3.90 - 4.10 B.M. The magnitude of

magnetic moment clearly indicates that all chelates are paramagnetic in nature,

with octahedral structures. The magnetic moment data are may be slightly lower

than three unpaired electrons which may be due to mixture of spin free

octahedral and tetrahedral geometries as predicted by Aggarwal and others 47, 48.

The low magnetic moments for d7 Co (II) ion may also be due to equilibrium

between low- spin and high- spin octahedral states. The complexes in which

magnetic moments (3.9 -4.88 B.M.) are slightly higher than three unpaired

electrons which may be due to the intrinsic orbital angular momentum in the

ground state, there is consistently a considerable orbital contribution. This

deviation from the spin only value (3.87B.M.) may be ascribed to spin orbital

coupling and suggest 49 an octahedral geometry for the Co (II) complex in the

high – spin state.

The Co (II) ion has the electron configuration d7, and its ground state

configuration in an octahedral ligand field may be either t2g5eg

2 in weak field or

t2g6eg

1 in strong fields. The ground term of Co (II) in octahedral environment is

4T1g or

2Eg depending on whether the complex is high spin or low-spin. The cobalt

(II) chelates shows three bands at 8928, 18518 and 21978 cm-1, which may be

assigned to the 4T1g →

4T2g (F),

4T1g →

4A2g (F) and

4T1g →

4T1g (P) transition

respectively in octahedral symmetry 50.


148

The electronic absorption spectra of Co (II) chelates are shown in fig .3.20

in chapter -3 and spectral data are summarized in table 3.17 in chapter -3.In

present work, the Co (II) complexes show three band in the regions 250-260 nm,

300-320nm and 500-561 nm these three band due to π→ π*or n→π* , C→T

or d-d transition for octahedral stereochemistry.

Magnetic properties and Electronic spectra of Zn(II) chelates

In present work, the magnetic moment determination shows that all the

complexes are diamagnetic nature. Therefore, they have no unpaired d-electron

in Zn (II), hence the complexes must be diamagnetic .The experimental data

coincident with theoretical prediction. The complexes are yellowish, which also

indicate the absence of unpaired electron. The structure may be tetrahedral or

octahedral 51-54.

In Zn (II),‘d ’ subshell is completely filled. There are no unpaired

electrons, hence, d-d transition are not possible in the complexes of Zn (II).

The electronic spectra of Zn (II) complexes exhibit bands in the range 414-

325 nm; 325-271nm and 251-258 nm which may be due to ligands transitions.

The electronic absorption spectra of Zn (II) chelates are shown in fig .3.24, in

chapter -3. The values are shown in table – 3.20 in chapter-3.They may be a

π→π*, n→π* transition. Most of complexes of Zn (II) are expected to be

tetrahedral. However, octahedral Zn (II) complexes are reported 55, 56.


149

Conclusion:-

The important point of the Schiff bases metal chelates are as follow.

1. Insoluble in water, methanol and other common organic solvent.

2. Soluble in polar organic solvent dimethyl sulfoxide, dimethyl formamide.

3. High melting point colored and stable in air.

4. Octahedral geometry.

5. The Co (II), Ni (II) and Cu (II) Schiff bases ligands chelates are

paramagnetic while Zn (II) Schiff bases ligands chelates are diamagnetic.

Based on the analytical, spectroscopy data, magnetic

measurements and thermal studies the following fig.6.1-6.3 tentative

octahedral structures has been proposed for all the Schiff bases ligands

chelates [ M (L1-o-v-A)(2H2O)], [M( L2-sal-A)(2H2O)], [M(L3-O-H-Naph-

A)(2H2O)]

NN

CH CH

O

M

O H2O

H2O

OCH3 H3CO

Fig.6.1


150

NN

HC HC

O

M

O H2O

H2O

Fig.6.2

NN

HC CH

O

M

O H2O

H2O

Fig.6.3


151

Where

M = Cu (II), Ni (II), Co (II), Zn (II)

(L1-o-v-A) =

6, 6’-(4, 4’-(cyclohexane-1, 1-diyl) bis (4, 1-phenylene)) bis (azan-1-yl-1- ylidene)

bis (methan-1-yl-1ylidene) bis (2methoxy phenol)

(L2 - sal – A) =

2, 2’-(4, 4’- (cyclohexane-1, 1-diyl) bis (4, 1-phenylene)) bis (azan-1-yl-1-ylidene)

bis (methan-1-yl-1-ylidene) diphenol

(L3 -o-H-Naph.-A) =

1,1’-(4,4’(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(azan-1-yl-1-ylidene)bis

(methan-1-yl-1-ylidene) dinaphthalen-2-ol


152

References :-

1. Theriot L. J.; Carlisle G. O.; Hu H. J. J. Inorg. Nucl. Chem. 31(9), 2891-

2894, (1969).

2. Fuzita L.; Nakamoto K.; Kobayashi M. J Amer. Chem. Soc. 78, 3963-

3965, (1956).

3. Madhu N.T.; Radhakrishnan P.K. Trans. Met. Chem. 25, 287-292, (2000).

4. Saxena V.K.; Gupta M.; Srivastava M.N. Synth. React. Inorg. Met-Org.

Chem. 26 (10), 1661-1676, (1996).

5. Mohapatra M.; Chakravortty V.; Dash K.C. Polyhedron 8 (12), 1509-1515,

(1989).

6. Koksal H.; Tumer M.; Serin S. Synth. React. Inorg. Met-Org. Chem. 26(9),

1577-1588, (1996).

7. Coltrain B.K.; Jackels S.C. Inorg. Chem. 20, 2032-2039, (1981).

8. Bellamy L.J. the Infrared Spectra of Complex Molecules, 3rd Edn. John

Wiley: New York, (1971).

9. Nawar N.; Hossny N. M. Trans. Met.Chem.15, 1-8, (2000).

10. Graber S.J.; Harris C.M.; Sinn E. J.Inorg.Nucl.Chem.30, 1805-1830,

(1968). Chem. Abstr. 69,73546s (1968).

11. Sharma B.D.; Bailar J.C., J. Am. Chem. Soc. 77, 5476, (1955).

12. Proceeding of the sixth international conference on thermal analysis

Bayrenth Germany (1980).

13. Icbudak H.; Yilmas V. T.; Olmes H. J. Thermal Anal. 53, 843(1998).

14. Issar Y.M.; Abdel Latif S.A.; Abu-El-Wafa S.M.; Abdel-Salam H.A. Synth.

Reac .Inorg. Met.-Org.Chem. 29 (1), 53, (1999).

15. Tumer M.; Köksal H.; Serin S., Synth. Reac .Inorg. Met.-Org. Chem. 27(5),

755, (1997).

16. Nakamoto K.; Lattice water and aqua and hydroxo complexes in infrared

and raman spectra of inorganic and coordination compound.4th Edn.; John

Wiley and sons, Ine .; New York, 227 (1986).


153

17. Arora D.L.; Lal K.; Gupta S.P. and Sahni S.K. polyhedron,10, 1499 (1986)

18. König E.; Structure and Bonding vol.9 springer- verlag, Berlin, Heidelberg

(1971).

19. Despande U.G. and Shah J.R. Die. Angew. Makro.Chem. 112,113 (1984).

20. Patel Y.M.; Shah J.R. Ind. J. Chem., 24, 800,(1986).

21. Despande U.G. and Shah J.R, J. Macromol. Sci.-Chem., A 21(1),21

(1984).

22. Larkworthy L.F. and Patel K.C. J. Inorg. Nucl. Chem., 32, 1271 (1970).

23. Despande U.G. and Shah J.R, J. Macromol. Sci.-Chem., A 23, 97 (1986).

24. Tomlinson A.A.G.; Hathaway B.J. J. Chem. Soc., 1685 (1968).

25. Basu G.; Belford R.L. and Dilkenson R.E., Inorg. Chem., 1, 438 (1962).

26. Mellor D.P.; Willis J.B.; Wales N.S., Proc. Roy. Soc., 79,141(1945).

27. Mellor D.P. and Willis J.B., J. Amer. Chem. Soc., 69, 1237 (1947).

28. Nyholm R.S., Chem. Rev., 53,263 (1953).

29. Sacconi L., Trans. Metal Chem., 4, 499 (1968).

30. Patel D.C. and Bhattacharya P.K., J. Ind. Chem. Soc., 49, 1041 (1972).

31. Ozha D.D.; Kaul K.N.; and Mehta R.K., Ind. J. Chem., 7, 927 (1969).

32. Johnson L. F.; Kamimura H., J. Chem. Phys., 38, 2579 (1963).

33. Lever A. B. P. J. Inorg. Nucl. Chem., 27, 149 (1965).


154

34. Jorgenson C.K., Acta. Chem. Scand., 9, 1362 (1955).

35. Liehr A. D.; Ballhausen C. J. Ann. Rev. Phy. Chem.,6, 134 (1959).

36. Buffagni S.; Vellerino L. M.; Quaglino J. V., Inorg. Chem., 3, 480 (1964).

37. Coussmaker C. R. C.; Hutchinson M. H.; Mellor J. R.; Sutton L. E.; Vanazi

L. M., J. Chem. Soc., 2705 (1961).

38. Maki G., J. Chem. Phys., 28, 651 (1958).

39. Musker W. K.; Haussain M. S., Inorg. Chem., 5, 1416 (1966).

40. Higginson W. C. E.; Nyburg S. C.; Wood J. S., Inorg. Chem., 3, 463

(1964).

41. El-tajory, A. N.; El-ajaily, M. M.; Malhub, A. A. ; Ben-Gweirif, S., Pure and

Applied Si. J., Sebha University, 5 (10), 108-123 (2006).

42. Figgis B. N.; Nyholm R. S., J. Chem. Soc., 388 (1959).

43. Figgis B. N., “Introduction to ligand fields ’’, Interscience Pub., New York,

p. 316 (1962).

44. Booth G.; Chatt J., J. Chem. Soc., 2099 (1962).

45. Cotton F. A.; Holm R. H., J. Am. Chem. Soc., 82, 2979 (1960).

46. Ballhausen C. J.; Gray H. B., Inorg. Chem., 1, 111 (1962).

47. Sinner E. J., J. Chem. Soc., 1237 (1960).

48. Suzuki I., Bull. Chem. Soc. Japan., 35, 1286, 1456 (1962).

49. Cotton F. A.; Wilkinson G. Advance Inorganic Chemistry, John Wiley and

Sons, New York (1988).


155

50. Lever A. B. P. “Inorganic Electronic Spectroscopy’’, Elsevier, London

(1968).

51. Suthar H. B.; Despande U. G.; Shah J. R., Bull. De. La. Soc. Chemieauq

De. France, 1, 55 (1986).

52. Syamal A.; Maurya M. R., Synth. Reac .Inorg. Met.-Org. Chem., 16,

39(1986).

53. White C.R.; Joesten M. D.; J. Inorg. Nucl. Chem., 38, 2113 (1976).

54. Syamal A.; Dutta R. L., “Elements of magneto Chemistry’’ 2nd. Ed.,

Afflicated East-West Press (P) Ltd., New Delhi (1982).

55. Singh B.; Maurya P. L.; Agrawal B. V.; Puri D. M., J. Chem. Soc., 68, 121

(1991).

56. Soni H. K.; Shah J. R., Bull. De. La. Soc. Chrmique. De. France, 2, 147

(1985).

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