Unit -5 COORDINATION CHEMISTRY

1. G0ve the dlfference between double salt and

coordination compounds.
SL.No Double Salt Co-ordination compound
1. |Dissociating into ions inNever dissociates to give
solutions. simple ions in solutions.
2 Loose their identity Does not loose its identity
3 Positive and negativeSimple and complex ions
|ions are present Jare present.
4. Example: Potash alum Example: K (Fe(CN)l
2. Define co-ordination number.
The number of ligand donar atom (or) no. of o-bond
bonded a central metal in a complex is called the
coordination number.
Ex: In K, [Fe(CN), the coordination number is 6
3. Write the postulates of Wemer's theory.
There are two types of valencies in metals namely.
a) Primary valency sky physics
b) Secondary Valency
PRIMARY VALENCY SECONDARY VALENCY
1. Oxidation number of the Co-ordination number of the
central metal ion. central metal ion.

2. lonisable valency -Non-ionisablevalency.

3. Satisfied by negative Satisfied by positive (or) negativel
ions.
ions (or) neutral molecules.
4. It is non-directional. Itis directional.
The
The inner sphere is called the coordination sphere.
outer sphere is caled the ionisation sphere.
Structure of [Co(NH),JCi,:
NH3 CI
H,N, NH,
CI Co
sky physics
H,N NH3
CI.
NH,
Limitation:
It does not explain the colour and magnetic properties
ofcoordination compounds.
4. Define crystal fleld stabilizing energy (CFSE)
It is the energy difference between the electronic
configuration of the ligand field and the bary centre.
CFSE (AE°)=[El-[Esol
5. Explain valence bond theony.
The ligand metal bond is covalent bond.
The ligand should contain at least one filled orbital with
a lone pair of electrons.
The central metal atom should contain vacant orbitals.
The vacant orbital of the metal atom Undergo
hybridisation.
The hybridised orbitals are directional in space and
give geometry to the complex.
Co-ordination number- 2, hybridisation- sp, Geometry
-Linear.
2
 Central metal atom with Unpaired electrons
paramagnetic while paired electron diamagnetic.
In octahedral complexes.
(n-1) d> low spin
nd >high spin
6. Calculate magnetic moment of Soordination compound
[CoF
Paramagnetic in nature
Unpaired electrons:4 sky physics
Ha|nn+2) 4+2) =24 = 4.9 BM.
7.Coordination compounds andtheir name.
1. [Ag (NH),JCI -Diamminesilver () chloride
2. [Ag (NH), -Diammine silver(1) ion
3. [Cu(NH), 1SO, -Tetra ammine copper (ll) sulphate
4. [Co (NH3), CI] - Penta ammine chlorido cobalt (1)
ion
5. (FeFs -Hexa fluorido ferrate (1) ion
6. (Fe (CN) -Hexa cyanido-KC ferrate (1) ion
7. Ks Fe (CN), NO] Potassium Penitacyanido - C
nitrosyl ferrate ()
8. [Cr (NHa, (H,0),JC, - Triammine triaqua chromium
(I) chloride.
8. [Ti (H,0)P is coloured while [Sc(H,0),J is colourless
explain.
(TI(H,0),J
TË3+ has one unpaired electron d1
d-d transition takes place
so it is coloured. 3
 (Sc(H,0)*
Sc3* has vacant do° orbital,
No unpaired electrons
No d-d transition
So it is colourless
of
9. What is the co-ordination entity formed when excess
liquid ammonia is added to an aqueous solution of copper
sulphate?
CuSO, +4NH, +[Cu(NH)J So,
sky physics
Tetrammine copper () sulphate
10. Why are Sc*, T, are colourless?
lon Configuration Reason
Sc3t, 3d No unpaired electrons No d
d-transition.
No unpaired electrons No d
Ts, 3do
|d-transition.

11. Why are Cu and Zn, are colourless?

lon Configuration Reason
Cut 3d10 Completely filled electrons
No d-d-transition.

Zn*, 3d10 Completely filled electrons

No d-d-transition.
12. Define crystal field splitting energy?
It is the energy associated with the absorbed
wavelength of light.
A =hc Y
A - crystal field splitting energy 4
h-Plank's constant
c -Velocity of light; Y -wave number
13. What are hydrate isomers? Explain with an example.
When solvent molecules llke water are exchanged by the
ligands in the crystal lattice of the coordination
compounds is called solvate isomerism.
Eg. (Cr(H,0),]cl, -Violet colour sky physics
[Cr(H,0)5 Ci] Cl,. H,0-Pale green colour
[Cr(H,0),C,] CI. 2H,0- Dark greencolour.
14. Whatare the limitations of VB theory?
1. It does not explain the colour of the complex
2. It does not consider the components of magnetic
moments.
3. It does not provide a quantitative explanation as to why
certain complexes are inner orbital complexes and the
others are outer ortbital complexes for the same metal.
15. Classify the folowing ligands based on the nümber of
donor atoms.
a) NH, b) en c)ox d) pyridine
Ligand Number of donar atomns Type of ligand
NH, Mono dentate
en 2 bi dentate
ox2 2 bi dentate
Pyridine 1 Mono dentate

16. Write the name of Ligand and central metal ion In [Ag
(NH),
Ligand -Ammine (NH,)
5
Central metal ion -Agt (silver () ion)
 does not exist why?
17. [CuCIj exits while [Cul
ICuC1J to CutTherefore
The chloride ion does not reduce Cu2*
xists.

[Cul,
The iodide ion reduces Cu2 to Cu Therefore does not
exist.

18. Arrange the following in order of increasing molar

conductivity.
() Mg [Cr(NH,) (C),l sky physics
(i) (Cr(NH,), Cl3 [CoFela
(iü) [Cr(NH), Cl¡l
[Cr(NH,),Ci]<Mg [Cr(NH,CIl<[Cr(NH,),CII, [CoFelz
19. Give an example of coordination compound used in
medicine and two examples of biologically important
coordination compounds.
Medicine:

Ca - EDTA chelate ’ in the treatment of lead and

radioactivity poisoning.
Cis-Platin >antitumor Vrugin cancertreatment.
Biologically important coordination compounds:
RBC Carying oxygen from lungs to tissues and CO,
from tissues to lunges.
Chlorophyll - Photosynthesis.
20. Based on VB theory explain why
[Cr(NH) J* 0s
paramagnetic, while [Ni(CN) J is diamagnetic. 6
 [Cr (NH4)J3 [NI (CN)J
Cr3+ 3d3 INi2 -3d8
NH, 0s weak field ligand CN - strong field ligand.
No pairing of 3d electrons Pairing of 3d electrons.
Number of unpaired Number of unpaired electron =
electrons =3 0

, =3(3+2) =3.872 BM
Paramagnetic Dlamagnetic

21. Asolution of [Ni (H,0),J2 ls green where as a solutlon

of [NI(CN)J is colourless -Explain. sky physics
(NI (H,0), [NI (CN)
H,O is a weaker ligand. CN is a strong ligand.
Don't pair d electrons. d- electrons are paired.
Presence of 2 unpaired Absence of unparied
electrons. electrons.
d-d transition occurs No d-d transition occurs
Green in colour. Colourless.
22. Central metal lon, oxidation state, ligands and
coordination number of various coordination compounds.
|K4IFe(CN)a [Ni(CO)1| (NI(en),JCl,
|Central metal ion Fe2+ Ni Ni2+
|Oxidation state +2 +2
Ligand CN
oCO en

|Coordination number 6
84 6

Complex ion (or) [Fe (CN)a [Ni (CO4)J Ni (en),12*

Coordination complex|

7
 isomerism, coordination isomerism
23. Explaln Linkage
and lonisation Isomerism In the coordination
compounds.
ligand is
Linkage isomerism: When an ambidentate central
bonded to two different donor atoms by the
metal ion are linkage isomers.
(Cr(H,0), NO,JBr and [Gr(H,0), ONOJBr
Coordination isomerism:
Coordination compounds
sky physics
having both the
cation and anion as complex ions give coordination
isomerism.
The ligands are interchange between the cationic and
the anionic complex.
[co(NH,).JICr (CN)]and [Cr(NH,)l [Co(CN)J
lonisation lsomerism:
When a simple ion act as a ligand and exchange with
one or more ligands present in the coordination sphere
0s called ionisation isomerism.
Eg: [Co(H,0), CIj|Br and [Co(H,0), Br] C.
24. Explain optical isomerism with an example.
Compounds with chiral atoms are optically active.
Enantiomers are optically active mirror images.
Dextro isomer: t rotates the plane of polarized light
towards the right.
Laevo isomer: It rotates the plane of polarized light
towards the left. ex.: [Co(en),13+
25. Why tetrahedral complexes do not exhibit
isomerism. geometrical
All the four ligands are adjacent to one
tetrahedral complexes. andther in
As the relative positions of donor atoms of ligands
attached to the central metal atom are same with
respect to each other.
8