Coordination Compounds _ Class Notes __ Backlog Killer For Class 12th JEE.pdf

Coordination Compounds
By – OM PANDEY, IIT - Delhi
Inorganic Chemistry
In One Shot

Topics
Introduction and Basic Terms
IUPAC Nomenclature
Werner’s Theory
Valence Bond Theory
Crystal Field Theory
Isomerism
1
2
3
4
5
6

Combination of two or more stable compounds
K2SO4 + Al2(SO4)3
Addition Compounds
KCl + MgCl2
addition compound, which lose their identity in aq. solution.
1. Double Salts
FeSO4 + (NH4)2SO4

Fe(CN)2 + 4 KCN
2. Coordination Compounds
addition compounds which do not lose their identity in aq. solution.
CuSO4 + 4NH3

Which of the following are the example of double salt ?
(II) CuSO4.4NH3.H2O
(IV) Fe(CN)2.4KCN
II and IV only
I, II and IV only
(I) FeSO4. (NH4)2SO4 . 6H2O
(III) K2SO4. Al2(SO4)3.24H2O
Choose the correct answer.
I and III only
I and II only
C
D
QUESTION (2023/01 Feb Shift-1)
A
B

K4 [ Fe (CN)6 ]
Co-ordination Entity
Co-ordination Sphere
Complex Ion
Counter Ion
Central Metal
Ligands
Co-ordination Number
Oxidation Number

No. of coordinate bonds that a ligand can form with Metal
Monodentate Bidentate Polydentate ligand
H2O
NH2
H2N
Chelation Ring Formation is known as chelation .
Chelates are generally more stable than non chelate complexes.
Denticity

ite ito
ide ido
ate ato
Cl–
3
CO 2–
NH –
F–
I–
Br –
Fluorido
Iodido
Bromido
Amido
Hydroxo
NO2
–
SO3
2–
Acetato
Oxalato
Sulphato
Thiosulphato
CH3COO–
C2O4
2–
SO4
2–
S2O3
2–
Hydrido
Cyano / cyanido
Oxo/oxido
Peroxido/peroxo
Superoxo
Nitrido
Azido
Sulphido
2
OH–
H–
CN –
O2–
O2
2–
O2
–
N3–
N3
–
S2–
Nomenclature

Triphenyl phosphene
Name
Aquo
Carbonyl
Nitrosyl
Ammine
Name
Nitrosonium
Hydrazinium
Ligands
NO+
N2H5
+
Dioxygen
Ligands
H2O
CO
NO
NH3
C5H5N Pyridine
CH3 – NH2 Methylamine
PPh3
O2
N2 Dinitrogen

Oxalato Glycinato
Dimethylglyoximato Acetylacetonato
Bidentate Ligand

Biurate Dipyridyl Ortho-phenanthroline
Bidentate Ligand

Polydentate Ligand
EDTA4–
dien Diethylene triamine

A polydentate ligand with different denticity
in different coordination compounds
SO4
2–
OCN–
NO2
–
Ligands that have more
than one kind of donor sites
CN–
SCN–
Flexidentate Ligand
Ambidendate Ligand

Co-ordination Number
[ Co(NH3)6]3+
[ Co(en)3]3+
Homoleptic Complex Hetero-leptic Complex

• Polyatomic ligands are enclosed in ( )
• No space between metal atom/ion & ligands
v For the coordination sphere, central atom first then ligands in alphabetical order.
[Cr(H2O)4Cl2] Cl
v Cation first followed by anion
K3 [Fe(CN)6] [Cr(H2O)4Cl2] Cl [Ag(NH3)2] [Ag(CN)2]
How to write a Coordination compound?

Cation is named first, followed by anion. [Cr(H2O)4Cl2] Cl
In naming of complex ion, the ligands are named first in the alphabetical order.
Use prefix di, tri, tetra for multiple ligands of same kind.
(H2O)4
If ligand’s name already contains any of these prefix, then we use bis, tris,
tetrakis instead of di, tri & tetra and name of ligand is enclosed in parenthesis.
(en)2
IUPAC name of a complex

If the complex ion is a cation, the metal is named same as the element.
[Cr(H2O)4Cl2]Cl
If the complex is anion, name of metal ends with the suffix –ate.

Cr chromium Chromate
Pt platinium platinate
Co cobalt cobaltate
Ni
Zn
Pd
Ti
Va
nickel
zinc
palladium
titanium
vanadium
nickelate
zincate
palladate
titanate
vanadate
Metal Name in Cationic part Name in Anionic part
Mo molybdenum molybdate

Pb
Ag
Au
Sn
Fe
lead
silver
gold
tin
iron
plumbate
argentate
aurate
stannate
ferrate
Metal Name in Cationic part Name in Anionic part

K3[Fe(CN)6]
Ni(CO)4
[ Ag(NH3)2 ] [ Ag(CN)2 ]

[NiCl2(pph3)2]
[Cr(NH3)3(H2O)3]Cl3
[Pt(NH3)5Cl]Br3
[Pt(NH3)2Cl4] Diammineterachloridoplatinum(IV)
Dichloridobis(triphenylphosphine)nickel (II)
Triamminetriaquachromium(III)chloride
Pentaamminechloridoplatinum(IV)bromide
(NH4)2 [ Ni(C2O4)2(H2O)2 ]
[Pt(H2NCH2CH2NH2)2 Cl2]Cl2
Fe(CO)5
Ammoniumdiaqua di(oxalato) nickelate(II)
Dichloridobis(ethylenediamine)platinum(IV)chloride
Pentacarbonyliron(0)

[Rh(NH3)5I]I2 Pentaammineiodidorhodium(III) iodide
[Fe(C2O4)3]3– Trioxalatoferrate(III) ion
[Cu(NH3)4]SO4 Tetraamminecopper(II) sulphate
NaCr(OH)4 Sodium tetrahydroxidochromate(III)
[Co(gly)3] Triglycinatocobalt(III)
[Fe(H2O)5(SCN)]2+ Pentaaquathiocyanato-S-iron(III) ion
K2[Hgl4] Potassium tetraiodidomercurate(II)
Practice

Dicyanidoaurrate(I) ion
Sodium hexafluoridoaluminate(III)
[Au(CN)2]–
Na3[AIF6]
[Cr(NH3)2(H2O)3(OH)](NO3)2
Diamminetriaquahydroxidochromium(III) nitrate
Barium dihydroxidodinitrito-O-oxalatozirconate(IV)
Pentaamminedinitrogenruthenium(II) chloride
Ba[Zr(OH)2(ONO)2(ox)]
[Ru(NH3)5N2]Cl2
[(CO)5Mn-Mn(CO)5]
Decacarbonyldimanganese(0)

CoCl3.5NH3 CoCl3.4NH3
CoCl3.6NH3
Modern Repn
No of Ions
Conductivity
Werner’s Theory

Primary Valency Secondary Valency
Ionisable Valency
Representation
NH3
NH3
NH3
H3N NH3
NH3
Co+3
…………
Cl …………Cl
…
…
…
…
Cl
Modern
Non-directional
CoCl3 . 6NH3
Non-ionisable Valency
Directional
Valences of Metal

A
B
C
D
QUESTION
The primary and secondary valencies of cobalt respectively in [Co(NH3)4Cl2] are :
[2023/24 Jan/Shift-1]
2 and 6
3 and 6
2 and 8
3 and 5

CH4
[ ZnCl4 ]2-
Valence Bond Theory

Coordination Number Type of Hybridisation Structure
It is usually possible to predict the geometry of a complex from the knowledge of its
magnetic behaviour on the basis of VBT.
Magnetic Behaviour

Magnetic moment - 5.9 BM
[FeF6]3–
Magnetic moment - 0 BM
[Co(NH3)6]3+

d1 d2
d3
d4 d5 d6 d7 d8
d9 d10
[ Sc (H2O)6 ]2+
[ Ti (H2O)6 ]2+
[ V(H2O)6 ]2+
[ Zn (H2O)6 ]2+
d0
[ Sc (H2O)6 ]3+
d-line for Hybridisation

Electrostatic Model
Ligands Point charges
Dipoles
which consider the metal – ligand bond to be ionic.
in case of anions
in case of neutral molecules
Z
x
y
x
Z
y
y
x
Z
y
x
Crystal Field Theory

Energy
M M
M
L
L
L
L
L
L
CFSE =
Crystal Field Splitting in ML6

eg
t2g
eg
t2g
eg
t2g
[ Ti (H2O)6 ]3+
[ Ti (H2O)6 ]2+
[ V(H2O)6 ]2+
CFSE =
Magnetic Moment =
Configuration =
CFSE =
Magnetic Moment =
Configuration =
CFSE =
Magnetic Moment =
Configuration =

d4
Configuration = Configuration =
CFSE = CFSE =
[Mn(CN)6]3–
[MnCl6]3–
Magnetic Moment = Magnetic Moment =

Halogen donors
I– Br – SCN–
Cl– F– OH– C2O4
2– H2O NCS–
S2– EDTA4– NH3 en CN – CO
Metal (+2) :
Metal (+3) :
Metal (+4) :
Co+3 [ C , N & O Donors ]
Oxygen donors Nitrogen donors Carbon donors
C donors
C & N donors Metal (+3)
Metal (+4)
All ligands are SFL
[ Co(NH3)6 ]3+ [ Rh(NH3)6 ]3+
[ Co(NH3)6 ]2+ [ CoCl6 ]3-
3d Series
Metal (+2)
4d / 5d Series
Spectrochemical Series

A
B
C
D
QUESTION
Which of the following is correct order of ligand field strength?
[2023/29 Jan/Shift-1]
S2– < C2O4
2– < NH3 < en < CO
S2– < NH3 < en < CO < C2O4
2
NH3 < en < CO < S2– < C2O4
2–
CO < en < NH3 < C2O4
2– < S2–

d6
Configuration
No. of unpaired
electrons
CFSE
Magnetic Moment
[ Fe(H2O)6 ]2+ [ Fe(CN)6 ]4-

[MnCl6]3–
[Mn(CN)6]3–
Predict Hybridisation with help of CFT ?

[Fe(CN)6]3–
[FeF6]3–
[Co(C2O4)3]3-
[CoF6]3–

Energy
y
x
z
CFSE =
Crystal field splitting in tetrahedral complex

d1
e
t2
d2
e
t2
d4
e
t2
d3
e
t2
Configuration =
CFSE =
Configuration =
CFSE =
Configuration =
CFSE =
Configuration =
CFSE =

QUESTION
The d-electronic configuration of [CoCl4]2– in tetrahedral crystal field is emt2
n. Sum of 'm'
and 'number of unpaired electrons is_______. [2023/24 Jan/Shift-1]

M
L
L
L
L
L
L
M
L
L
L
L
Crystal Field splitting in square complex

[ I– to H2O ] [ NH3 to CO ]
d8 d9
PtCl4
2–
Ni(CN)4
2–
NiCl4
2–
[Cu(NH3)4]2+
3d series (+2 Metal)
4d / 5d series (+2/+3/+4)
C.N. = 4
d0 d7 d8 d9 d10 ZnCl4
2–
MnO4
–
PdCl4
2–
Tetrahedral & Square Planar
Zn(CN)4
2–
CrO4
2-

[NiCl4]2–
[Ni(CN)4]2
–
[Ni(CO)
4]
Predict Hybridisation with help of CFT ?

[Ti(H2O)6]3+
Colour in Co-ordination compounds

A = [ Co(NH3)6 ]2+ B = [ Co(NH3)6 ]3+
lAbsorbed : A B
lObsorbed : A B

Coordination Comp. Wavelength of light
absorbed (nm)
Colour of light
absorbed
Colour of
coordination entity
[CoCl(NH3)5]2+
[Co(NH3)5(H2O)]2+
[Co(NH3)6]3+
[Co(CN)6]3–
[Cu(H2O)4]2+
535
500
475
310
600
Yellow
Blue Green
Blue
Ultraviole
t
Red
Violet
Red
Yellow Orange
Pale Yellow
Blue
Data
Analysis

A B
C D
QUESTION
Match List I with List II [2023/25 Jan/Shift-2]
Choose the correct answer from the options given below :-
A-III, B-II, C-I, D-IV
A-IV, B-I, C-III, D-II
A-I, B-III, C-IV, D-I
A-III, B-I, C-II, D-IV
List I Coordination entity List-II wavelength of light
absorbed in mm
A. [CoCl(NH3)5]2+ I. 310
B. [Co(NH3)6]3+ II. 475
C. [Co(CN)6]3– III. 535
D. [Cu(H2O)4]2+ IV. 600

Ligand to Metal Metal to Metal
Fe3+ + [Fe(CN)6]4 –
CrO4
2-
MnO4
-
Prussian blue
Fe2+ + [Fe(CN)6]3 –
Turn bulls blue
Charge transfer spectra
Purple
Yellow

[Ni(dmg)2]
Hybridisation & Geometry = No of unpaired electrons =
Colour = Rosy Red / Scarlet Red No of rings =
It acquires stability through chelation and intra molecular H-bonding.

CuSO4 .
5H2O
Hybridisation & Geometry =
Colour = Bright Blue
Hydrate of copper(II) sulfate is Bright Blue, while its anhydrous form is white .
Blue Vitriol

Salt Analysis
Brown Ring Complex

The metal-carbon bond in metal
carbonyls have both σ and p character.
M C O
The metal to ligand bonding creates a synergic effect which strengthens the bond
between CO and the metal
[Mn(CO)6]+ [Cr(CO)6] [V(CO)6]– [Ti(CO)6]2–
[Ni(CO)4] [Co(CO)4]– [Fe(CO)4]2–
M ___ C Bond length
C ___ O Bond length
Bonding in Metal Carbonyls

EAN = Z – n + 2 * C.N.
[Co(NH3)6]3+
[Fe(CN)6]4–
[Mn(CO)6]
Stability of Co-ordination Compound
[Mn(CO)6] can act as a reducing agent because the metal carbonyl is stable when
EAN is equal to the nearest noble gas configuration by losing one electron.
Effective Atomic Number

Structural Isomerism
Ionisation Isomerism
Hydrate Isomerism
Linkage Isomerism
Co-ordination Isomerism
Stereo- Isomerism
Geometrical Isomerism
Optical Isomerism
Ligand Isomerism
Isomerism in Coordination Compound

Same molecular formula but give different ions in solution on ionization.
[Co(NH3)5Br]SO4
[Co(NH3)5SO4]Br
[CoBr(NH3)5]SO4
[CoSO4(NH3)5]Br
AgNO3
BaCl2
AgNO3
BaCl2
Experimental Proof
Ionization Isomerism

same molecular formula, but differ in the number of water molecules outside
the coordination sphere.
Hydrate Isomerism
CrCl3. 6H2O [Cr(H2O)6 ]Cl3
AgNO3
[Cr(H2O)5Cl]Cl2
. H2O
AgNO3
[Cr(H2O)4Cl2 ]Cl. 2 H2O
AgNO3
Order of Weight Loss by using Dehydrating agent :
[Cr(H2O)3Cl3 ]. 3 H2O
AgNO3

Same Molecular formula but different linkage
b/w metal and ligand Ambidentate ligands
[ Co(NO2)(NH3)5 ]2+
Linkage Isomerism

Polynuclear Complexes : Partial or complete exchange of ligands between
complex ions.
[ Co(NH3)6 ] [ Cr(CN)6 ]
Coordination Isomerism

pn
tn
propylenediamine
trimethylenediamine
[ Co(NH3)4pn]2+
[ Co(NH3)4tn]2+
Ligand Isomerism

Same connections among atoms = Same Structure
Stereoisomers
Geometrical isomers Optical isomers
Different arrangement of the atoms in space
Stereoisomers

Angle between two ligands must be different
Pt(NH3)2Cl2
Geometrical isomers
Pt(NH3)4Cl2

Ma4
Ma3b
Ma2b2
G.I. in Square Planar Complex O.I. in Square Planar

Ma2bc
Mabcd
[Pt NH3 Br Cl Py ]

G.I. & O.I. in Tetrahedral Complex

Ma6 Ma5b
Ma2b4
Geometrical & Optical isomerism in Octahedral

M(AA)a4
M(AA)2a2
[Co(en)2Cl2]+

Cr
N
N
N
N
N
N
[Cr(en)3]3+
N
N N
N
N
N
N
N
N
N N
N
N
N N
N
N
N
POS in [Cr(en)3]3+

[Co(gly)3]3+
GI = OI = SI =
Enantiomeric pairs =
O
Co
O
N
O
N
N
Co
N
O
O O
N
N
Co
O
N
O O
N
N
Co
N
N
O O
N
O

The complex cation which has two isomers is
[Co(NH3)5Cl]2+
[Co(NH3)5Cl]+
[Co(NH3)5NO2]2+
[Co(H2O)6]3+
A
B
C
D
QUESTION (2023/01 Feb/ Shift-2)

Chiral complex from the following is ( here en = ethylene diamine )
Trans-[PtCl2(en)2]2+
trans-[Co(NH3)4Cl2]+
cis-[PtCl2(NH3)2]
cis-[PtCl2 (en)2]2+
A
B
C
D
QUESTION (2023/29 Jan/ Shift-1)

Which of the following can’t show isomerism ?
[Ni(en)3]2+
[Ni(NH3)4(H2O)2]2+
[Pt(NH3)2Cl2]
[Ni(NH3)2 Cl2]
A
B
C
D
QUESTION

Industry and Natural Uses
Chlorophyll → Green Pigment Responsible for photosynthesis
→ Co-ordination compound of Mg
Haemoglobin → Red pigment of blood
→ Acts as oxygen carrier
→ Co-ordination compound of Fe
Vitamin B12 ( Cyanocobalamine )
→ Co-ordination compound of Co
Cis platin Cis-(Pt(NH3)2Cl2)
→ To inhibit the growth of tumours.
Wilkinson catalyst [(Ph3P)3RhCl]
→ used for hydrogenation of alkenes.

Carbonic Anhydrase
→ Catalyze the inter conversion between CO2 & H2O and H2CO3
→ Coordination compound of Zn
Penicillamine → Chelating agent ( Binds with Cu )
→ Treatment of Wilson’s disease.
Desferrioxamine B → Chelator ( Binds with Fe)
EDTA → Treatment of Pb poisoning
v Note : Hardness of water is estimated by simple titration with Na2 EDTA.
Carboxy peptidase A
→ Removes the amino acid residue from the c-terminal of a peptide chain
→ Coordination compound of Zn

Coordination Compounds _ Class Notes __ Backlog Killer For Class 12th JEE.pdf

Coordination Compounds _ Class Notes __ Backlog Killer For Class 12th JEE.pdf

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