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B.Sc. II YearInorganic Chemistry

B-206

1

Dr. Sachin Kumar

Assistant Professor

Sanjay Gandhi (P.G.) College

Sarurpur Khurd , Meerut

Syllabus is covered in Four unitsSubtopics of each units are written below

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Unit IV

Oxidation & Reduction, Acids & Bases, Non-aqueous Solvents

Unit III

Chemistry Of lanthanides Elements Chemistry Of Actinides

Unit II

Coordination Compounds

Unit I

Chemistry of Elements of First Transition Series

Chemistry of Elements of Second & Third Transition Series

Question paper Patterns

Total Marks 50

Minimum Marks 17

• Full question paper is divided into five sections.

• Section A contain Q. 1 only

• Section B contains Q. 2 & Q. 3

• Section C contains Q. 4 & Q. 5

• Section D contains Q. 6 & Q. 7

• Section E contains Q. 8 & Q. 9

• In total, Solve Five question only.

• Section A will be short answers type and remaining

• four sections will be descriptive types.

Section A:

Question no.1 is compulsory and has ten short answer type questions. Each question carrying 2 marks. Questions will come from all four sections. (total marks 10)

Section B:

Question no. 2 & 3 are descriptive type and will come from first section only. Do any one question from Question no. 2 & 3 .(total marks 7.5)

Section C:

Question no. 4 & 5 are descriptive type and will come from second section only. Do any one question from Question no. 4 & 5 .(total marks 7.5)

Section D:

Question no. 6 & 7 are descriptive type and will come from third section only. Do any one question from Question no. 6 & 7 .(total marks 7.5)

Section E:

Question no. 8 & 9 are descriptive type and will come from fourth section only. Do any one question from Question no. 8 & 9 .(total marks 7.5)

Question paper Pattern

Unit II

Coordination Compounds

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Sub-Topic

Werner’s Coordination Theory and its experimental verifications,

Effective Atomic Number Concept, Chelates

Nomenclature of Coordination Compounds,

Isomerism in Coordination Compounds

Valence Bond Theory of Transition Metal Complexes

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Books Consulted & Recommended

1. Principles of Inorganic Chemistry Puri, Sharma , Kalia Milestone Publishers

2. Concise Inorganic Chemistry J. D. Lee Blackwell Science

3. Inorganic Chemistry James E. Huheey,

E. A. Keiter, R. L. Keiter Harper Collins College

4. Inorganic Chemistry Shriver & Atkins W. H. Freeman and Company New York

5. Inorganic Chemistry Malik, Tuli, Madan S. Chand

6. Elements of Chemistry N. N. GREENWOOD & BUTTER WORT H E N E M A N N

A. EARNSHAW

Books Writers Publications

Coordination Compounds

When two or more stable compounds in stoichiometric

proportions are allowed to crystalize together, new

compounds are separate out.

1. Double Salt

Examples:

Mohr Salt, Potash alum

2. Coordination Compounds

Examples:

K4[Fe(CN)6], [Cu(NH3 4]

2+

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Double Salts/ Addition Compounds/ Molecular Compounds

• Those compounds are those compounds which exist only in crystal lattice(solid state) but loose their identity in solution.

• KCl + MgCl2 + 6H2O KCl.MgCl2.6H2O (Carnalite)

(In solution, K+ , Cl- , Mg2+ In solid state behave as one compound

can be identified as

individual component.)

Solutions of double salts have the same physical properties as a mixture of individual components

Similarly, FeSO4. (NH4)2SO4.6H2O (Mohr’s Salt) & Al2(SO4)3.K2SO4.24H2O (Potash Alum) behave as Double Salts. 8

Complex Compound/ Coordination Compounds/ Coordinate Complex Compound

Formed by coordinate

covalent bond

Complexes compounds are

shown by [] square bracket.

The chemistry of metal ion in

solution is essentially the chemistry of

their complex.

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K4[Fe(CN)6]

[Cu(NH3)4]2+

Examples

Fe

CN-

CN-

CN-CN-

CN-

CN-

4

4 K+

𝑲𝟒 𝑭ⅇ 𝑪𝑵 𝟔 → 𝟒𝑲+ + 𝑭ⅇ 𝑪𝑵 𝟔𝟒 −

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Some Other Definitions…

• “A Complex is a molecule/ion containing a central metal atom/ion surrounded by a definite number of ligands held by secondary valency's or coordinates bonds”

• “A neutral complex or ionic compound in which one of the ions is complex”

• “A complex is a combination of a Lewis acid (the metal ion) with a number of Lewis base(the Ligand)”

• “The term complex means a central metal atom or ion surrounded by a set of ligands”.

• “A coordination compound, or complex, is formed when a Lewis base (ligand) is attached to a Lewis acid (acceptor) by means of a "lone-pair" of electrons”.

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Some Historical background

❑Werner coordination theory in 1893 was the first attempt to explain the bonding in coordination complexes.

❑It was an imaginative theory as electron was still not discovered as well as the electronic theory of valency was not established.

Which year electron was discovered??

❑Alfred Werner was awarded Noble prize in Chemistry in the year 1913 for his contribution to the inorganic chemistry.

❑He was curious why a stable salt CoCl3 react with another stable molecule NH3 to form various new compounds.

❑Without bonding and structure theory and also without X-ray diffraction(most powerful method to establish structure of crystals), he and his students were able to explain the nature of bonding in the complexes.

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Werner’s theory

Werner’s theory

According to him, Metal shows two different types of valency in the complexes.

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Primary Valencies Secondary Valencies

❑ These are ionizable and non directional.

❑ The Primary valencies is the number of charges

present on the complex ion.

❑ The primary valency is called oxidation state in

the modern technology.

❑ These are non- ionizable and directional.

❑ The Secondary valencies is equal to the number of

ligands coordinated to the metal.

❑ Every metal has a fixed no. of secondary valencies.

❑ The secondary valency is called coordination number

in the modern technology.

❑ Due to direction properties, it leads to the geometry &

stereo-chemistry of the molecule

Central metal tends to satisfy both the valencies.

Fe

CN-

CN-

CN-CN-

CN-

CN-

4

𝐾4 𝐹ⅇ 𝐶𝑁 6 → 4𝐾+ + 𝐹ⅇ 𝐶𝑁 64 −

❖ Count no. of arrows /number of CN-

pointed towards Fe atom, it’s six.

❖ Secondary valency : 6

❖ Octahedral geometry

❖ Ligands are also called donor atoms since

❖ they form coordinate bond with metal

❖ In the complex the oxidation state of

Fe atom is + 2.

❖ Primary valency : 2

❖ Non directional

❖ Fe is also called Acceptor atoms since it

accepts electrons from ligands

Square bracket is called Coordination sphere

Fe atom is called central atom.

CN -is called ligand(that gives one or

more electron pairs to the central atom)14

Remember : NO electron, NO X-RD

• Werner combined the interpretation of optical and geometrical iso-merisms, pattern of reactions and conductance data in his work and create a model of how to use physical and chemical evidence effectively and imaginatively.

• Four complexes of Cobalt (III) with ammonia had been discovered and named according to their colors.

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Complex Color Early Name

CoCl3. 6NH3 Yellow Luteo Complex

CoCl3. 5NH3 Purple Purpureo Complex

CoCl3. 4NH3 Green Praseo Complex

CoCl3. 4NH3 Violet?/Red Violeo Complex

Same complex but

Two different colors

Why?????

NH3

NH3

NH3

NH3

NH3

NH3

Co

Cl

Cl Cl

[Co(NH3)6]Cl3

NH3

NH3

NH3

Co

NH3

H3N NH

3

Cl

Cl

Cl

[CoCl3(NH3)3](NH3)3

NH3

NH3

Cl

NH3

NH3

NH3

Co

NH3

Cl Cl

[CoCl3(NH3)5](NH3)(Cl)2

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Which structure is correct??

Experimental Verification

Reactivity of all Chloride ions in these four compounds are different to a extent. He observed that:

CoCl3. 6NH3 + excess Ag+ 3 AgCl ppt

CoCl3. 5NH3 + excess Ag+ 2AgCl ppt

CoCl3. 4NH3 + excess Ag+ 1 AgCl ppt

Also with the loss of one Ammonia atom function of chlorine atoms starts Changing (ionic to covalent)

If all chlorine atoms are same than in

all the complex compounds 3 AgCl

should be precipitated!!

He concluded that cobalt is showing a constant coordination number of Six. We should considered the oxidationstate of the metal and also its coordination number also.

He used cryoscopic measurement (like: depression in freezing points) to find out the number of ionic particles.

He measures the conductivities of large number of coordination compounds to find out the number of ions in solutions.

He also postulate that bonds present in the complexes were fixed in space and therefore applications of structural principles can be applied to them.

17By means of number and geometries of the compounds he successfully assigned the correct structures of many compounds.

Remember : NO electron, NO X-RD

• CoCl3.6NH3 [Co(NH3)6]3+ + 3 Cl- (Total 4 ions)

• CoCl3.5NH3 [CoCl(NH3)5]2+ + 2 Cl- (Total 3 ions)

• CoCl3.4NH3 [CoCl2(NH3)4]1+ + Cl- (Total 2 ions)

• CoCl3.6NH3 [CoCl3(NH3)3] + 3 NH3 (Total ??ions)

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Cryoscopic Measurement

[Co(NH3)6]Cl3 Cobalt oxidation state is +3 which is balanced by 3 Chlorine atoms.

Secondary Valency/Coordination number of Cobalt is six due to 6 ammonia molecules are coordinated to cobalt atom(Central atom).

Cobalt is a acidic centre as it accepts electron pairs from ammonia.

Ammonia is called Ligand (basic center) because it donates electron pairs to cobalt.

Due to six coordination number the geometry of this complex is Octahedral.

Stereo chemistry of coordinated compounds is also simplified due to geometry.

Result

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Solid lines shows secondary valency/coordination number

Dash lines represent primary valency

NH3

NH3

NH3

NH3

NH3

NH3

Co

Cl

Cl Cl

[CoCl(NH3)5]Cl2

NH3

NH3

NH3

NH3

NH3

Co

Cl

Cl Cl

[CoCl2(NH3)4]Cl

NH3

NH3

NH3

NH3

Co

Cl

Cl Cl

CoCl3.5NH3 CoCl3.4NH3

Cl

One Chlorine atom is satisfying both

primary and secondary valency of Cobalt

Two Chlorine atom is satisfying both

primary and secondary valency of Cobalt20

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Do you remember ?? Same complex but Two different colors

Why?????

They are geometrical isomers .

SimilarlyMolecular

Formula

Number of particles

From cryoscopic

measurements

Molar Conductance

Ʌm , (S m2 mol-1)

Number of electrical

charges determined

from ʌm

Structure of Complexes

PtCl4.6NH3 5 524 8 [Pt(NH3)6]4+ 4 Cl-

PtCl4.5NH3 4 404 6 [PtCl(NH3)5]3+ 3 Cl-

PtCl4.4NH3 3 230 4 [PtCl2(NH3)4]2+ 2 Cl-

PtCl4.3NH3 2 97 2 [PtCl3(NH3)6]1+ Cl-

PtCl4.2NH3 1 0 0 [PtCl4(NH3)2]

KPtCl5.NH3 2 109 2 K+ [PtCl5(NH3)]-1

K2PtCl6. 3 256 4 2K+ [PtCl6]2-

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PtCl4.6NH3

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NH3

NH3

NH3

NH3

NH3

NH3

Pt

Cl

Cl Cl

Cl

Alfred WernerThe Nobel Prize in Chemistry 1913

• Born: 12 December 1866, Mulhouse, France (now Germany (now France))

• Died: 15 November 1919, Zurich, Switzerland

• Affiliation at the time of the award: University of Zurich, Zurich, Switzerland

• Prize motivation: "in recognition of his work on the linkage of atoms in molecules by which he has thrown new light on earlier investigations and opened up new fields of research especially in inorganic chemistry.“

Work

• The world around us consists of molecules that are composed of atoms. Charting the bonds and positions of atoms in space is one of chemistry's fundamental missions. In 1893 Alfred Werner contributed to the understanding of molecular structures of inorganic substances -chemical compounds that do not contain carbon. According to Alfred Werner, the attractive forces are not connected to certain directions in the atom but emanate uniformly from the middle of the atom. With a new coordination number for an atom's bonds, he shed light on the structures of substances. 24https://www.nobelprize.org/prizes/chemistry/1913/werner/facts/

Nomenclature of Coordination Compounds

❑1. Orders of naming ions❑Cation name is written first followed by anion name with a gap in between them.

❑2. The neutral/non-ionic are written in one word name.

❑3. Naming of Coordination sphere ❑Ligands are named alphabetically followed by central atom/metal name

❑Ligand number(quantity) is not needed for deciding alphabetically order.

❑Do not give any space between ligands names and metal atoms.

❑After metal name the metal oxidation state is written in roman numeral in small bracket without giving any extra space in between.

❑4. Within coordination sphere, ligand name(IUPAC name) is written and outside the coordination sphere, common name of the ligands is written. (Why?)

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Rules:

Contd…

• 5. Four type of complexes can be found• [], [neutral molecule], [Ni(CO)4]

• []X [cationic]+ X-[Ag(NH3)2]Cl

• X[] X+[anionic]- K4[Fe(CN)6]

• []+ []- [cationic]+ [anionic]- [Pt(NH3)4][PtCl4]

• 6. Ligands numbering: it is used only, if more that one type of each particular ligand present in the coordination sphere only.(Numerical prefixes)• di, tri, tetra, penta, hexa, hepta, octa, nona, deca, etc.(Always written in Italicize text)

• In [M(NH3)4)] will be written as tetra ammine…………. (it’s not full name!!)

• In [M(Cl)2 (NH3)2] will be written as di ammine di chloro…...(it’s not full name!!)

• Another type of prefixes is used to avoid confusion in naming• bis, tris, tetrakis, etc.

ligand name is written only after it’s quantity is written.26

•7. Names of Ligands:• The names of negative charge ligands end in o and that of positive charge

ligands end in ium.

• Generally the neutral ligands are name as such.

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Negative Ligands IUPAC

Names

Negative

Ligands

IUPAC

Names

Positive

Ligands

IUPAC Names

Cl- /Chloride Chloro/Chlorido SO42-/Sulphate Sulphato NO+/Nitroso Nitrosonium

Br- /Bromide Bromo CO32-/ Carbonate Carbonato NO2

2+/ Nitronium

l- /Iodide Iodo NO2-/ Nitrite Nitrito-N NH2-NH3

+ /

Hydrazide

Hydrazinium

F- /Fluoride Fluoro ONO-/Nitrite Nitrito-O

CN-/Cyanide Cyano H-/ Hydride Hydrido Neutral

Ligand

IUPAC Names

CH3COO-/Acetate Acetato NH-/ Imide Imido NH3 Ammine

-OOC-COO-/ Oxalate Oxalato NCS-/Thiocyanide Thiocyanato-N C5H5N Pyridine

NH2-/Amide Amido NO3-/Nitrate Nitrato H2O Aqua

SCN-/Thiocyanide Thiocyanato-S OH-/ Hydroxide Hydroxo CO Carbonyl

Contd…• 8. Ending Of Metal names:

• Only when the complex is anionic , the central metal name ends in ate. • In some cases of anionic complexes, the Latin name of metal is used.• For example,

• Cuperate for Cu, Ferrate for Fe Argentate for Ag

• Stannate for Sn Aurate for Au

• 9. Abbreviations for complicated molecules is used• For, ethyelendiamine molecule en is used.• For, Pyridine Py is used.• For, acetylacetato acac is used.

• 10. Outside coordination sphere usual ligand name without their number/quantityshould be written.

• 11. Inside coordination sphere ligands IUPAC names with their quantity must be written.

• Some More rules will added later on………….28

Let’s Start [Ag(NH3)2]Cl you can also think of this molecule as [Ag(NH3)2]

+ Cl-

• 1. First looking on the coordination sphere [], we observe that :• only one type of ligand NH3 (Ammonia) is present and the IUPAC name of ammonia is “ammine”• Two molecule of ammonia are present and we will use Di for two molecules• ligand NH3 (Ammonia) is neutral molecule (No Charge).• Central atom is silver(Ag). • Our complex is cationic [Ag(NH3)2]

+.• Oxidation state of Ag is +1. How?? Two ways to calculate: Let X be the Oxidation State of Ag

• [Ag(NH3)2]Cl [Ag(NH3)2]+

• X(Ag) + 2 x (charge of NH3) + charge of Cl- = 0, so (X(Ag) + 2 x (charge of NH3) = charge on complex, so• X + 2 x 0 + (-1) = 0, X comes out to be 1. X + 2 x 0 = 1, X comes out to be 1.

• 2. Outside coordination sphere only one molecule of chloride ion is present

• Let’s write IUPAC name of the above compound

• DiammineSilver(I) Chloride29

K4[Fe(CN)6]• you can also think of this molecule as 4 K+ [Fe(CN)6]

4-

• 1. First looking on the coordination sphere [], we observe that :• only one type of ligand CN-(Cyanide) is present and the IUPAC name of cyanide is “Cyano”• Six molecule of a cyanide are present and we will use Hexa for six molecules.• Cyanide ion (CN- ) carry one negative charge. Potassium (K+) carry one positive charge.• Central atom is Iron(Fe). • Our complex is anionic [Fe(CN)6]

- , so metal name ends with ate. Latin name of Fe is “Ferrate”• Oxidation state of Fe is +2. How?? Two ways to calculate: Let X be the Oxidation State of Fe

• K4[Fe(CN)6] [Fe(CN)6]4-

• 4 x (charge of K+ ) + X(Fe) + 6 x (charge of CN-) = 0, so X(Fe) + 6 x (charge of CN-) = charge on complex, so• 4 x (+1) + X + 6 x (-1) = 0, X comes out to be +2. X + 6 x (-1) = -4, X comes out to be +2.

• 2. Outside coordination sphere four molecules of Potassium ion are present.(outside ligands

numbering is not needed)

• Let’s write IUPAC name of the above compound

• Potassium hexacyanoferrate(II) 30

[Ni(CO)4]• 1. First looking on the coordination sphere [], we observe that :

• Only one type of ligand CO (carbonmonooxide) is present and the IUPAC name of CO is “carbonyl”• Four molecules of CO are present and we will use tetra for four molecules• ligand CO (carbonmonooxide) is neutral molecule (No Charge).• Central atom is Nickel(Ni). • Our complex is neutral .• Oxidation state of Ni is 0. How?? • Here only one way to calculate: Let X be the Oxidation State of Nickel

• [Ni(CO)4]• X(Ni)+ 4 x (charge of CO) = 0, so

• X + 4 x 0 = 0, X comes out to be 0. .

• 2. Outside coordination sphere nothing is present.

• Let’s write IUPAC name of the above compound

• Tetracarbonylnickel(0) 31

[Co(NO2)3(NH3)3]• 1. First look on coordination sphere [], we observe that

• Here two type of ligands Nitrite and Ammonia are present and the IUPAC names of nitrite is “Nitrito-N” and IUPAC names of ammonia is “Ammine”

• Three molecule each of Nitrite ion and ammonia molecule are present and we will use tri for three • Nitrite ion (NO2

- ) carry one negative charge. Ammonia (NH3) carry zero charge (neutral molecule).• Ammine will be written first followed by nitrito-N as alphabetically order has to be maintained.• Central atom is Cobalt(Co). • Our complex is neutral.• Oxidation state of Co is +3. How?? One way to calculate: Let X be the Oxidation State of Cobalt

• [Co(NO2)3(NH3)3]• X(Co) + 3 x (charge of NO2

-) + 3 x (charge of NH3) = 0, soX + 3 x (-1) + 3 x 0 = 0, X comes out to be +3.

• 2. Outside coordination sphere nothing is present.

• Let’s write IUPAC name of the above compound

• Triamminetrinitrito-NCobalt (III)• Triamminetrisnitrito-NCobalt (III)

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[Co(Cl)(ONO-)(en)2]+

• 1. First look on coordination sphere [], we observe that • Here three type of ligands Chloride (Cl- ), Nitrite ion (ONO- ) and en (2HNCH2CH2NH2) are

present and here en is used as abbreviation for ethylenediamine.• IUPAC names of Chloride is “Choloro/Chlorido” , Nitrite ion (NO2

- ) is “Nitrito-O” and ethylenediamine is “1,2-ethylenediammine ”.

• two molecule of ethylenediamine are present and we can use di/bis for two molecules• Chloride ion (Cl- ) carry one negative charge. Nitrite ion (NO2

- ) carry one negative charge. ethylenediammine (2HNCH2CH2NH2) carry zero charge (neutral molecule).

• Chloro should be written first, subsequently ethyelenediamine and then nitrito-O as, alphabetically order has to be maintained.

• Central atom is Cobalt(Co). Our complex is ionic/cationic.• Oxidation state of Co is +3. How?? to calculate: Let X be the Oxidation State of Cobalt

• [Co(Cl)(ONO-)(en)2]+

• X(Co) +1 x (charge of Cl-) + 1 x (charge of ONO-) + 2 x (charge of 2HNCH2CH2NH2) = +1, soX + 1 x (-1) + 1 x (-1) + 2 x 0 = 1, X comes out to be +3.

• Let’s write IUPAC name of the above compound• Chloro1,2-etyhlenediaminenitrito-OCobalt (III)

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Forget to notice molecule has charge also,

Chloro1,2-etyhlenediaminenitrito-OCobalt (III) ion

Some More Examples

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[Pt(Cl)3(NH3)3]+ triamminetrichloroplatinum(IV) ion

K[BF4] Potassium tetrafluoroborate(III)

Na2[Ni(EDTA)] Sodium ethylenediaminetetraacetatonickelate(II)

[Cr(H20)6]Cl3 Hexaaquachromium(III) Chloride

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Some New rules and examples will be coming soon.

Till then practice some few more names by yourself

Thank You

If any queries/doubt are present, feel free to write an email to sachin2282@gmail.com orwrite down in your note book and contact me in the college.