TOPIC : 1. Introduction to complex, coordination chemistry. 2. Ligands explained (with eg) 3. Classification of complexes (with eg) 4. EAN effective atomic number (with eg)

1. BIOCHEMISTRY
TOPIC :
1. Classification of complexes
2. EAN (eg)
3. Nomenclature (eg)
- MINHAJUL ABEDEN
- GOVERNMENT SCIENCE COLLEGE AUTONOMOUSUS,
BANGALORE
COORDINATION CHEMISTRY

2. 1. Ligands definition
● ion/atom
● 1 or more donor atom
● Each donate 1 pair of e-
● I.e lewis base
1. Classification
1. based on how the ligands bond to CMA
● Monodentate
● Bidentate
● Polydentate
● Ambidentate
● chelating
1. Based on charge of complex formed
● Cationic
● Anionic
● neutral
2.3 Based type of ligands
● Homoleptic
● heteroleptic

3. 1. LIGANDS
An ion or molecule that binds to a central metal atom to form a coordination complex & the
binding force is ccordination bond.

4. CLASSIFICATION
1.1 Based on their donor atoms [number of donor atoms]
1. MONODENTATE ligand
Ligand donate 1 pair of e-
To bond to CMA by one bond
2. BIDENTATE
2 pair of e-
2 bonds to CMA
3 POLYDENTATE
more than 2
more than 2 bonds to CMA

5. 1.2 Number of donor atoms
a. Ambidentate
More than 2 donor atoms
Ligates thru one donor atom
a. Chelating
Polydentate ligands
1 ligand Ligates thru 2 donor atoms
Forms ring strusture

6. e

7. 1.3 Based on charge of complex formed
a. Anionic
The coordination complex is -vely charged (when ionic sphere removed)
a. Cationic
a. Neutral
NOTE :
the ligands can also
be classified based on
charge on the ligand specie:
i.e Neutral,
Cationic,
anionic ligand

8. 1.4 BASED ON TYPE OF LIGAND (complexes are classified)
a. Homoleptic complex
only one type of ligand
[Co(NH3)6]3+
a. Heteroleptic
more than one type of ligands
[Co(NH3=)4 Cl2]+

9. EAN (eff atomic number)
Total number of e- present with the CMA (includes the e - donated by ligands).
The CMA accepts e- to complete octate confn
EAN= Z - X + Y
Z atomic num. of CMA
X e- lost by CMA on cmplx frmn
y e- gained frm ligand

10. EAN concept explained :
EAN = eff. atomic num.
EAN = total num of e- present with CMA including those donated by ligands
(in stable complex)
EAN = the number is always equal to atomic no. of nearest noble gas
(nearest to metal in periodic table)
EAN answer is always equal to Z of noble gas
EAN = (total no. of e- in CMA) + (no. of e- donated by ligands)
EAN = [(atomic no. Of CMA) - (Oxydn state of CMA)] + [no. e- donated by ligands]
EAN = (z) - ( x ) + [ y ]
EAN = z-x+y
● Oxidation state is subtracted from Z because many times metals have +ve O.S i.e they lost e-
● eg Fe2+ have 24 e- compared to ground state config on 26

11. Solving EAN
1. Note the atomic no. of CMA at ground state = Z
2. Find out O.S of CMA = x
3. Determine coordination number = y
4. Substitute in
EAN = Z-X+Y
Note
its necessary to remember
- atomic number & oxidation state of transition elements
- names and formula of important complexes

12. EAN examples
1. Potassiunferrocyanide K4 [ Fe (CN)6 ]
Note : EAN = Z - X +Y
Ferro : +2 charge
CN has -1 charge in its ionic stage
[ Fe (CN)6 ] is the coon sphere
K4 is the ionic sphere
a. Calculate O.S of Fe (Fe loses two e- to become Fe2+ with 24 electrones)
( that will be the X)
-4 = X - 6
X = +2
a. (Coordination num) * 2 = Y
Y = 2 * 6
Y= 12
a. Z = atomic number
Z = 26
EAN = 26 - 2 + 12
EAN = 36 ( i.e the config of noble gas Krypton )
Ean of potassiumferrocyanide is 36 hence its a stable complex

13. 2 . Potassiunferricyanide K3 [ Fe (CN)6 ]
Note : EAN = Z - X +Y
Ferro : +3 charge
CN has -1 charge in its ionic stage
[ Fe (CN)6 ] is the coon sphere
K3 is the ionic sphere
a. Calculate O.S of Fe (Fe loses three- to become Fe3+ with 23 electrones)
( that will be the X)
-3 = X - 6
X = +3
a. (Coordination num) * 2 = Y
Y = 2 * 6
Y= 12
a. Z = atomic number
Z = 26
EAN = 26 - 3 + 12
EAN = 35
Ean of potassiumferricyanide is 35 , IT ACTS AS OXYDISING AGENT

14. 3. Cupraammoniumsulphate [ Cu (NH3)4 ​] SO4
Note : EAN = Z - X +Y
Cupra: +2 charge
Sulphate has -2 charge in its ionic stage
[Cu (NH3)4 ] is the coon sphere
SO4 is the ionic sphere
a. Calculate O.S of Cu (Cu loses two e- to become Cu2+ with 29 electrones)
( that will be the X)
-2 = X - 4
X = +2
a. (Coordination num) * 2 = Y
Y = 2 * 4
Y= 8
a. Z = atomic number
Z = 29
EAN = 29 - 2 + 8
EAN = 35
Ean of Cupraammoniumsulphate is 35 IT ACTS AS OXYDISING AGENT