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COORDINATION COMPOUNDS

Sy l labus :

Introduction to co-ordination compounds, Werner’stheory; ligands, co-ordination number, denticity,chelation; IUPAC nomenclature of mononuclearco-ordination compounds, isomerism; Bonding-Valence bond approach and basic ideas of Crystalfield theory, colour and magnetic properties;Importance of co-ordination compounds (inqualitative analysis; extraction of metals and inbiological systems).


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CO-ORDINATION COMPOUNDS

C1 Double Salts and Co-ordination Compounds

Double Salts : are those which loose their identity in solution as alum.[K

2SO

4.Al

2(SO

4)

3.24H

2O]

Co-ordination Compounds (Complexes) : Those which retain their identity in solution(complexes) as potassium ferrocyanide, K

4[Fe(CN)

6].

A complex (or co-ordination compound) is a compound consisting either complex ionswith other ions of opposite charge.

K4[Fe(CN)

6] K+ is other ion

complex anion

[Pt(en)3]Cl

4Cl– is other ion

complex cation

[Pt(en)2Cl

2]

neutral complex

Ligands : A Ligand is a species that is capable of donating an electron pair(s) to a centralion. It is a Lewis base. In accepting electron pairs, the central ion acts as a Lewis acid.

Ligand can be (a) unidentate

(b) bidentate, tridentate, tetradentate etc.

(c) Ambidient

Unidentate Ligand : Ligand is said to be unidentate if it has only one pair of electronsthat it can donate.

Polydentate Ligand : Ligand is said to be bidentate, tridentate, tetradentate etc.depending on the number of electron pairs that it can donate.

(a) :NH3 ; one electron pair available for donation oxidentate.

(b) two electron pairs available for donation bidendate

Some common Multidentate Ligands (Chelating Agents)

Abbrevation Multi Name Formulae Charge

en bidentate ethylenediame 0

ox bidentate oxalate –2

gly bidentate glycinate –1


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DMG bidentate dimethyl glyoximate –1

EDTA hexadentate ethylenediamine

tetraacetate –4

Chelates : Some ligands are capable of donating more than a single electron pair, fromdifferent atoms in the ligand and to different sites in the geometric structure of a complex.These are called as multidentate ligands. When the bonding of a multidentate ligand tometal ion produces a ring (usually five or six membered) we refer to the complex as achelate. The multidentate ligand is called a chelating agent and the process of chelateformation is called chelation

Nickel (II) dimethylglyoximate (chelate)

[bis-(dimethylglyoximato) nickel (II)]

Co-ordination Number : The co-ordination number of a metal atom in a complex is thetotal number of bonds the metal atom forms with Ligands.

C2A Nomenclature : Following rules are adopted for naming a complex ion.

(a) cations are named before anions.

(b) oxidation state (O.S.) of the central metal ion is denoted by Roman numeral

Cation O.S. Anion

CuC2

Copper (II) chloride

FeCl3

Iron (III) chloride

(c) The names of ligands are given first followed by the name of central metal ion.

(d) The names of ligands that are anions and ending with

‘ide’ changed to ‘o’

‘ite’ changed to ‘ito’

‘ate’ changed to ‘ato’


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(e) Some Common Unidentate Ligands

Neutral Anions (replacing ‘ide’ by ‘o’)

Formula Names as Ligand Formula Name as Ligand

H2O aqua F–(Fluoride) Fluorido

NH3

ammine Cl– Chlorido

CO Carbonyl S–2 sulphido

NO nitrosyl H– hydrido

CH3NH

2methyl amine O–2 (oxide) oxo

C5H

5N or Py Pyridine OH– (hydroxide) hydroxo

(C2H

5)

3N Triethylamine CN–(cyanide) cyano*

(C6H

5)

3N Tripphenyl amine NC isocyano*

[* marked are ambident)

Replacing ‘e’ by ‘o’

SO4

2– sulphato

S2O

32– thiosulphato

CO3

2– carbonato

NO2

– nitro*

ONO– nitrito*

SCN– thiocyanato*

NCS– isothiocyanato*

(e) Positive groups end in-ium

NH2 – NH

3+ hydrazinium

(f) When there are several ligands of the same kind we normally use the prefix di, tri, tetrasoon. If the name of ligand includes a number e.g. ethylenediamine (en). To avoidconfusion in such cases, bis, trix and tetrakis are used.

e.g. bis (ethylenediammine)

(g) If anion is a complex then metal ends with ‘ate’ [Ni(CN)4]2–

tetracyanonickelate (II) ion

lead – plumbate gold – Aurate

tin – stannate silver – argentate

iron – ferrate copper – cuprate

(h) If the complex contain two or more metal atoms, it is termed polynuclear. The bridgingligands which link the two metal atoms together are indicated by the prefix


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(i) Ambidient Ligands may be attached through different atoms

M – NO2

(NO2) joined to metal M through N; it is nitro

M – ONO (NO2 joined to metal M through O it is nitro)

Similarly the SCN group may bond M-SCN (thiocyanato) or (M – NCS) (isothiocyanato).They may be named as

thiocyanato – S, thiocyanato – N

C2B When writing (not naming) the formulae of the complex

complex ion should be enclosed by square brackets.

Ligands are place after metal in the alphabetical order but first negative ligands,then neutral then positive.

[Pt(NH3)

2 (H

2O)

4] – correct;

])NH()CN(Cr[

neutral

23

negative

4 – correct

Example :-

1.

anioncation

Anion

6

cation

4

errate(II)hexacyanofPotassium

][Fe(CN)K

anion is complex hence metal ends with ate.

Ligands are named before metal ion of complex.

2.anion

3

cation

63 Cl])NH(CO[

Hexaammine cobalt (III) chloride

3. [CO(en)3]Cl

3

Tris (ethylenediammine) cobalt (III) chloride

4. [Pt(Cl)2(NH

3)

4]Cl

2

Tetraamminedichloroplatinum (IV) chloride

[NH3(ammine) and Cl(chloro) are written in alphabetical order]

5. In the following examples complex ion exist as cation :-

(a) [Fe(NH3)

6]Cl

3 Hexaammine iron (III) chloride

(b) [CoCl(NH3)

5]2+ Pentaamminechlorocobalt (III) ion

(c) [CoSO4(NH

3)

4]NO

3 Tetraamminesulphatocobalt (III) nitrate

6. Complex ion exist as anions :-

(a) [ZnCl4]2– Tetrachlorozincate (II) ion

(b) [AlH4]— Tetrahydridoaluminate (III) ion


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(c) Na3[Ag(S

2O

3)

2] Sodium bis (thiosulphato) argentate (I)

(d) Na2 [OSCl

5N] sodium pentachloronitrido osmate (VI)

(e) K2[Cr(CN)

2O

2(O

2)NH

3] Potassium amminedicyanodioxo peroxochromate (VI)

7. Organic Ligands have been used :-

(a) [Pt(Py)4] [Pt Cl

4] Tetrapyridineplatinum (II) tetrachloroplatinate (II)

(b) [Cr(C6H

6)

2] Bis (benzene) chromium (O)

(c) [Fe(C5H

5)

2] Bis (cyclopentadienyl) iron (II)

C2C (EAN) Effective Atomic Number :

Each ligand donates an electron pair to the metal ion, thus forming a co-ordinate bond

EAN = Z – O.N. + 2 (C.N.)

ON oxidation number

or C.N. co-ordination number

EAN = Z – O.N. + 2 (Ligands)

(assuming that each ligand is unidentate)

C3 Isomerism in Complexes :-

Compounds having same chemical formulae but differ structural arrangements are calledisomers.

Structural isomerism :-

Differ from each other. How the atoms are joined together that is in the order in which theatoms are bonded to each other.

H – N = C = O and N C – O – H are structural isomer.

Ionisation Isomerism :-

This type of isomerism occurs when there is an interchange of groups between theco-ordination sphere of the metal ion and the ions outside this sphere. Examples are :

[CO(NH3)

5 (SO

4]Br [CO(NH

3)

5Br] SO

4

[give yellow ppt. with Ag+] [give white ppt. with Ba2+ as SO4

2— beingion as Br– outside the bracket ionisable]is ionisable]

Co-ordination isomerism :-

When both positive and negative ions are complex ions. Isomerism may be caused due tointerchange of ligands between anion and cation. This arises only when cation and anionhave same C.N. and charge

(a) [CO(NH3)

6]3+ [Cr(CN)

6]3— same charge

&

[Cr(NH3)

6]3+ [CO(CN)

6]3— same O.N.


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Linkage Isomerism :-

(i) [CO(NH3)

5ONO]Cl

2 and [CO(NH

3)

5NO

2]Cl

2

(ii) [Mn(CO)5 (SCN)]+ [Mn(CO)

5(NCS)]+

Hydrate Isomerism :-

Hydrate isomers of a complex that differ in the placement of water molecules in the com-plex CrCl

3.6H

2O can be written as

[Cr(H2O)

6]Cl

3— violet (anhydrous)

[Cr(H2O)

5Cl]Cl

2.H

2O — light green (monohydrate)

Stereo Isomers :-

1. Geometrical

2. Optical

Geometrical :- are isomers in which the atoms are joined to one another in the same waybut differ because some atom occupy different relative position in space.

Geometrical Isomers of C.N. – 4

(a) [Pt(NH3)

2Cl

2]

(b)

Geometrical isomers of C.N. – 6

(a) [CO(NH3)

4Cl

2]+


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(b) [Pt(NH3)Cl

2Br

2]

(c) [Pt(NH3)

3Cl

3]

Optical Isomerism :- If a molecule is asymetric that it cannot superimposed on its mirrorimage. The two forms have the same type of symmetry shown by the left and right handsand are called enantiomeric pair. The two forms are called optical isomers. They are calledeither dextro or leavo (dor l).

Optical isomerism is common in octahedral complexes involving bidentate ligands.

[CO(en)2Cl

2] exists as cis and trans but cis-form can have optical isomerism.


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C4A Werner’s theory of co-ordination compounds :

1. There are two types of valency shown by central metal atom/metal ion in a compound

(a) Primary (b) Secondary

Primary Valency corresponds to oxidation number and secondary valency correspondsto co-ordination number.

In the complex [CO(NH3)

6]Cl

3, primary valency is satisfied by three Cl, secondary

valency is six.

In [CO(NH3)

4(H

2O)

2]SO

4, four NH

3 and two H

2O (ligands) satisfy secondary valency.

One SO42— satisfy primary valency.

Primary valency is ionisable.

The secondary valencies are directional and are responsible for isomerism in complexes.

The primary valencies are non-directional and is represented by ..... and secondaryvalency by _______________


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In all cases, metal or metal ions should satisfy primary and secondary valency both. Somenegative ions can satisfy primary as well as secondary valency both.

e.g. [Cr(NH3)

5Cl]Cl

2 satisfy both primary and secondary valency.

Practice Problems :

1. Explain the bonding in coordination compounds in terms of Werner’s postulates.

C4B Bonding in complexes

The metal m loses required no. of electrons to form cation. No. of electrons lost corre-spond to O.N.

The metal ion makes available a no. of empty orbitals equal ot its co-ordinates number forthe formation of co-ordinates bonds with the Ligand Orbitals.

A weak ligand like (H2O, halide) will not affect the electronic configuration of the metal/

metal ion.

A strong ligand like (NH3, CN—, CO) affect the electronic configuration of the metal/

metalion. They make unpaired electrons paired.

The metal ion orbitals hybridise to form a new set of equivalent hybridised orbitals.

If there are unpaired electrons in the complex it is called paramagnetic.

Magnetic moment = )2N(N B.M.

N no. of unpaired electrons.

The complex with so many unpaired electrons is high spin complex and that with pairedelectrons is low spin complex.

If inner d-orbital is used for hybridisation it is called inner d complex. e.g. d2sp3 [Fe(CN)6]4–

If outer d-orbital is used is called outer d-complex. sp3d2

Weak field ligand [Fe(H2O)

6]3+

I— < Br < S2– < Cl— < NO3— < F— < oxalate < H

2O < EDTA < NH

3 < en < NO

2— < CN—

< CO

Examples : [Fe(CN)6]4— O.N. = +2

C.N. = 6

[six empty orbitals are required by six CN— ligands] t2g d

xy, d

yz, d

zx e.g. dx2 – y2, dz2


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Complex ion is d2sp3 hybridised Inner d-complex

Diamagnetic Magnetic moment = O

Octahedral geometry

[Fe(H2O)

6]3+

(H2O is weak ligand)

Hybridisation – sp3d2 Outer-d-complex

Paramagnetic (High spin complex) Octahedral geometry


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State o f H

ybrid

isatio n an

d M

agne tic B

ehaviou

r of some co-o rd

ination

comp

lex

Metal

Com

pl ex

Metal

IonC

onfig u

rationof m

eta l ion

Hyb

ridisation

of meta l ion

orbital s for

ligand

bon

ds

No. of u

np

airedelectro n

sM

agne tic

Beh

avi our

[V(H

2 O)

6 ]3

+V

3+

d2

sp3d

22

Param

a gnetic

[Cr(N

H3 )

6 ]3

+C

r3

+d

3d

2sp3

3P

arama gnetic

[Mn

F6 ]

3—

Mn

3+

d4

sp3d

24

Param

a gnetic

[Mn(C

N)

6 ]3

—M

n3

+d

4d

2sp3

2P

arama gnetic

[Fe(C

N)

6 ]3

—F

e3

+d

5d

2sp3

1P

arama gnetic

[Fe(F

6 )]3

—F

e3

+d

5sp

3d2

5P

arama gnetic

[Fe(C

l4 )]2

—F

e2

+d

6sp

34

Param

a gnetic

[CO

F6 ]

3—

CO

3+

d6

sp3d

24

Param

a gnetic

[CO

(CN

)6 ]

3C

O3

+d

6d

2sp3

0D

iamag netic

[Ni(C

l)4 ]

2—

Ni 2

+d

8sp

32

Param

a gnetic

[Ni(C

N)

4 ]2

—N

i 2+

d8

dsp2

0D

iamag netic

[CO

Cl4 ]

2—

CO

2+

d9

sp3

1D

iamag netic

[Zn(N

H3 )

4 ]2

+Z

n2

+d

10

sp3

0D

iamag netic


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E X E R C I S E (OBJECTIVE)

1. The EAN of Ni in Ni(CN)42– is

(a) 34 (b) 35

(c) 36 (d) 28

2. Glycinato ligand is

(a)

(b) Bidentate ligand

(c) Two donor sites N and O–

(d) All

3. The compound which does not showparamagnetism

(a) [Cu(NH3)

4]Cl

2(b) [Ag(NH

3)

2Cl

(c) NO (d) NO2

4. Which one is bidentate ligand

(a) C2O

42–

(b) NH2·CH

2·CH

2·NH

2

(c) Both

(d) None

5. Which ion is paramagnetic

(a) [Ni(NH3)

4]2+ (b) [Ni(CO)

4]

(c) [Co(NH3)

6]3+ (d) [Ni(CN)

4]2–

6. The shape of the complex Ag(NH3)

2+ is

(a) Octahedral (b) Square planar

(c) Tetrahedral (d) Linear

7. K3CoF

6 is high spin complex. What is the hybrid

state of Co atom in this complex

(a) sp3d (b) dp3d2

(c) d2sp3 (d) dsp2

8. Which one of the following will be able to showcis-trans isomerism

(a) MA3B (b) M(A A )

2

(c) MA2BCD (d) MA

4

9. The type of isomerism shown by [Co(en)2(NCS)

2]Cl

and [Co(en)2(NCS)Cl]NCS is

(a) Co-ordination (b) Ionisation

(c) Linkage (d) All above

10. Which of the following cations does not form anamine complex with excess of ammonia

(a) Ag+ (b) Cu2+

(c) Cd2+ (d) Na+

11. Hexafluorocobaltate (III) ion is found to be highspin complex, the probable hybrid state of cobaltin it is

(a) d2sp3 (b) sp3

(c) sp3d (d) sp3d2

12. In sodium tetrafluorooxochromate(.....),Na

3[Cr(O)F

4] the left out place should be filled with

which of the following Roman numericals

(a) VI (b) III

(c) IV (d) none of these

13. The correct name of the compound[Cu(NH

3)

4](NO

3)

2, according to IUPAC system is

(a) Cuprammonium nitrate

(b) Tetraammine copper(II) dinitrate

(c) Tetraammine copper(II) nitrate

(d) Tetraammine copper(I) dinitrate

14. Lithium tetrahydridoaluminate is correctlyrepresented as

(a) Al[LiH4] (b) Al

2[LiH

4]

3

(c) Li[AlH4] (d) Li[AlH

4]

2

15. The correct IUPAC name of K2[Zn(OH)

4] is

(a) Potassium tetrahydroxyzinc(II)

(b) Potassium tetrahydroxozincate(II)

(c) Potassium tetrahydroxyzincate(IV)

(d) Potassium hydroxozinc(II)

16. The correct IUPAC name of KAl(SO4)

3 · 12H

2O is

(a) Aluminium potassium sulphate-12-water

(b) Potassium aluminium(III) sulphate-12-water

(c) Potassium aluminate(III) sulphatehydrate

(d) Aluminium(III) potassium sulphatehydrate-12

17. Number of electrons gained by Pd in [PdCl4]–2;

(a) 4 (b) 8

(c) 10 (d) Zero

18. The possible number of isomers for the complex[MCl

2Br

2]SO

4 is

(a) 1 (b) 2

(c) 4 (d) 5

19. The oxidation number of Pt in [Pt(C2H

4)Cl

3]– is

(a) +1 (b) +2

(c) +3 (d) +4


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20. Chlorophyll is a co-ordination compound havingcentral atom of

(a) Ca (b) Mg

(c) Na (d) K

21. Among [Ni(CN)4]2– [NiCl

4]2– and [Ni(CO)

4]

(a) Ni(CN)22– is square planar and NiCl

42–

and Ni(CO)4 are tetrahedral

(b) NiCl42– is square planar and Ni(CN)

42–


(c) Ni(CO)4 is square planar and Ni(CN)

42–

and [NiCl4]2– are tetrahedral

(d) None

22. Which one does not belong to ligand

(a) PH3

(b) NO+

(c) BF3

(d) Cl–

23. Nickel metal is in highest oxidation state in

(a) Ni(CO)4

(b) K2NiF

6

(c) [Ni(NH3)

6](BF

4)

2(d) K

4[Ni(CN)

6]

24. A complex of cobalt has five ammonia molecules,one nitro group and two chlorine atoms for eachcobalt atom. One mole of this compound producesthree moles ions in aqueous solution which ontreating with excess of AgNO

3 give two moles of

AgCl. The formula of the compound is

(a) [Co(NH3)

4NO

2Cl][(NH

3)Cl]

(b) [Co(NH3)

5Cl][ClNO

2]

(c) [Co(NH3)

5NO

2]Cl

2

(d) [Co(NH3)

5][(NO

2)

2Cl

2]

25. K3[Al(C

2O

4)

3] is called

(a) Potassium alumino oxalate

(b) Potassium alumino (III) oxalate

(c) Potassium trioxalato aluminate

(d) Potassium trioxalato aluminate (III)

26. In hexacyanomanganate (II) ion the Mn atomassumes d2sp3 hybrid state. The number of unpairedelectrons in the complex is

(a) 1 (b) 2

(c) 3 (d) zero

27. Name the metal M which is extracted on the basisof following reactions

4M + 8CN– + 2H2O + O

2 4[M(CN)

2]– + 4OH–

2[M(CN)2]– + Zn [Zn(CN)

4]2– + 2M

(a) Nickel (b) Silver

(c) Copper (d) Mercury

28. The colour of [Ti(H2O)

6]3+ is due to

(a) Transfer of an electron from one Ti toanother

(b) Presence of water molecule

(c) Excitation of electrons from d d

(d) Intramolecular vibration

29. The number of d-electrons in [Cr(H2O)

6]3+ is

(a) 2 (b) 3

(c) 4 (d) 5

30. Ammonia forms the complex ion [Cu(NH3)

4]2+ with

copper ions in alkaline solutions but not in acidicsolutions. What is the reason for it ?

(a) Copper hydroxide is an amphotericsubstance

(b) In acidic solution hydration protectscopper ions

(c) In acidic solutions protons coordinateswith ammonia molecules forming NH

4+

ions and NH3 molecules are not available

(d) In alkaline solution insoluble Cu(OH)2 is

precipitated which is soluble in excessof any alkali

31. In the coordination compound, K4[Ni(CN)

4], the

oxidation state of nickel is

(a) +2 (b) –1

(c) 0 (d) +1

32. The coordination number of a central metal atomin a complex is determined by

(a) the number of ligands around a metal ionbounded by sigma bonds

(b) the number of ligands around a metal ionbounded by pi-bonds

(c) the number of ligands around a metal ionbonded by sigma and pi-bonds both

(d) the number of only anionic ligandsbonded to the metal ion.

33. Which one of the following complexes is an outerorbital complex ?

(a) [Fe(CN)6]4– (b) [Mn(CN)

6]4–

(c) [Co(NH3)

6]3+ (d) [Ni(NH

3)

6]2+

[Atomic nos. : Mn = 25, Fe = 26, Co = 27, Ni = 28]

34. Cerium (Z = 58) is an important member of thelanthanoids. Which of the following statmenetsabout cerium is incorrect ?

(a) The common oxidation states of ceriumare +3 and +4

(b) The +3 oxidation state of cerium is morestable than +4 oxidation state

(c) The +4 oxidation state of cerium is notknown in solutions

(d) Cerium (IV) acts as an oxidising agent.


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A N S W E R S

1. a

2. d

3. b

4. c

5. a

6. d

7. b

8. c

9. b

10. d

11. d

12. b

13. c

14. c

15. b

16. b

17. b

18. d

19. b

20. b

21. a

22. c

23. b

24. c

35. The correct order of magnetic moments (spin onlyvalues in B.M.) among is

(a) [MnCl4]2– > [CoCl

4]2– > [Fe(CN)

6]4–

(b) [MnCl4]2– > [Fe(CN)

6]4– > [CoCl

4]2–

(c) [Fe(CN)6]4– > [MnCl

4]2– > [CoCl

4]2–

(d) [Fe(CN)6]4– > [CoCl

4]2– > [MnCl

4]2–

36. The IUPAC name of the coordination compoundK

3[Fe(CN)

6] is

(a) Potassium hexacyanoferrate (II)

(b) Potassium hexacyanoferrate (III)

(c) Potassium hexacyanoiron (II)

(d) Tripotassium hexacyanoiron (II)

37. Which of the following compounds shows opticalisomerism ?

(a) [Cu(NH3)

4]2+ (b) [ZnCl

4]2–

(c) [Cr(C2O

4)

3]3+ (d) [Co(CN)

6]3–

38. Which one of the following cyano complexes wouldexhibit the lowest value of paramagneticbehaviour ?

(a) [Cr(CN)6]3– (b) [Mn(Cn)

6]3–

(c) [Fe(CN)6]3– (d) [Co(CN)

6]3–

[At. Nos : Cr = 24, Mn = 25, Fe = 26, Co = 27)

39. The value of the ‘spin only’ magnetic moment forone of the following configurations is 2.84 BM. Thecorrect one is

(a) d4 (in strong ligand field)

(b) d4 (in weak ligand field)

(c) d3 (in weak as well as in strong field)

(d) d5 (in strong ligand field)

40. The IUPAC name for the complex[Co(NO

2)(NH

3)

5]Cl

2 is

(a) pentaamminenitrito-N-cobalt(III)chloride

(b) nitrito-N-pentaamminecobalt(III)chloride

(c) nitrito-N-pentaamminecobalt(II)chloride

(d) pentaamminenitrito-N-cobalt(II)chloride

41. Nickel (Z = 28) combines with a uninegativemonodentate ligand X– to form a paramagneticcomplex [NiX

4]2–. The number of unpaired

electron(s) in the nickel and geometry of thiscomplex ion are, respectively

(a) two, square planar

(b) one, tetrahedral

(c) two, tetrahedral

(d) one, square planar

42. In Fe(CO)5, the Fe-C bond possesses

(a) -character only

(b) -character only

(c) both and characters

(d) ionic character

43. The “spin-only” magnetic moment [in units of Bohrmagneton. (µ

B)] of Ni2+ in aqueous solution would

be (atomic number Ni = 28)

(a) 1.73 (b) 2.84

(c) 4.90 (d) 0

44. How many EDTA (ethylenediaminetetraacetic acid)molecules are required to make an octahedralcomplex with a Ca2+ ion ?

(a) Two (b) Six

(c) Three (d) One

25. d

26. a

27. b

28. c

29. b

30. c

31. c

32. a

33. d

34. c

35. a

36. b

37. c

38. c

39. a

40. a

41. c

42. c

43. b

44. d


New Delhi – 110 018, Ph. : 9312629035, 8527112111

CCC – 16

TEST YOURSELF

ANSWERS

1. b

2. a

3. c

4. b

5. c

6. d

7. a

8. b

9. c

10. b

1. Chlorophyll is a co-ordination compound havingcentral atom of

(a) Ca (b) Mg

(c) Na (d) K

2. Among [Ni(CN)4]2– [NiCl

4]2– and [Ni(CO)

4]

(a) Ni(CN)22– is square planar and NiCl

42–


(b) NiCl42– is square planar and Ni(CN)

42–


(c) Ni(CO)4 is square planar and Ni(CN)

42–

and [NiCl4]2– are tetrahedral

(d) None

3. Which one does not belong to ligand

(a) PH3

(b) NO+

(c) BF3

(d) Cl–

4. Nickel metal is in highest oxidation state in

(a) Ni(CO)4

(b) K2NiF

6

(c) [Ni(NH3)

6](BF

4)

2(d) K

4[Ni(CN)

6]

5. A complex of cobalt has five ammonia molecules,one nitro group and two chlorine atoms for eachcobalt atom. One mole of this compound producesthree moles ions in aqueous solution which ontreating with excess of AgNO

3 give two moles of

AgCl. The formula of the compound is

(a) [Co(NH3)

4NO

2Cl][(NH

3)Cl]

(b) [Co(NH3)

5Cl][ClNO

2]

(c) [Co(NH3)

5NO

2]Cl

2

(d) [Co(NH3)

5][(NO

2)

2Cl

2]

6. K3[Al(C

2O

4)

3] is called

(a) Potassium alumino oxalate

(b) Potassium alumino (III) oxalate

(c) Potassium trioxalato aluminate

(d) Potassium trioxalato aluminate (III)

7. In hexacyanomanganate (II) ion the Mn atomassumes d2sp3 hybrid state. The number of unpairedelectrons in the complex is

(a) 1 (b) 2

(c) 3 (d) zero

8. Name the metal M which is extracted on the basisof following reactions

4M + 8CN– + 2H2O + O

2 4[M(CN)

2]– + 4OH–

2[M(CN)2]– + Zn [Zn(CN)

4]2– + 2M

(a) Nickel (b) Silver

(c) Copper (d) Mercury

9. The colour of [Ti(H2O)

6]3+ is due to

(a) Transfer of an electron from one Ti toanother

(b) Presence of water molecule

(c) Excitation of electrons from d d

(d) Intramolecular vibration

10. The number of d-electrons in [Cr(H2O)

6]3+ is

(a) 2 (b) 3

(c) 4 (d) 5

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