CHEMISTRY TEXTBOOK

Try this...

Give VBT description of

bonding in each of following

complexes.

a. [ZnCl 4 ]^2

b. [Co(H 2 O) 6 ]^2 ⊕ (high spin)

c. [Pt(CN) 4 ]^2 (square planar)

d. [CoCl 4 ]^2 (tetrahedral)

e. [Cr(NH 3 ) 6 ]^3 ⊕

vi. Six orbitals available for hybridisation

are two 3d, one 4s, three 4p orbitals

3d 4s 4p

d^2 sp^3

The orbitals for hybridization are decided

from the number of ammine ligands which

is six. Here (n-1)d orbitals participate in

hybridization since it is the low spin complex.

vii. Electronic configuration after complex

formation.

3d 4s 4p

d^2 sp^3

Co

NH 3

NH 3

NH 3

NH 3

H 3 N

H 3 N

3 ⊕

Remember...

Complete the missing entries.

Coordination

number

Geometry

of complex

Hybridisation

2 sp

4 Tetrahedral

4

Square

planar

6 d^2 sp^3 / sp^3 d^2

9.9.2 Octahedral, complexes
a. [Co(NH 3 ) 6 ]^3 ⊕ low spin
i. Oxidation state of Cobalt is +3
ii. Valence shell electronic configuration
of Co^3 ⊕ is represented in box diagram as
shown below :
3d 4s 4p

iii. Number of ammine ligands is 6, number
of vacant metal ion orbitals required for
bonding with ligands must be six.
iv. Complex is low spin, so pairing of electrons
will take place prior to hybridisation.
v. Electronic configuration after pairing would
be
3d 4s 4p

viii. As all electrons are paired the complex is

diamagnetic.

b. [CoF 6 ]^3 high spin

i.Oxidation state of central metal Co is +3

ii.Valence shell electronic configuration of

Co^3 ⊕ is

3d 4s 4p

iii. Six fluoride F ligands, thus the number of

vacant metal ion orbitals required for bonding

with ligands would be six.

iv. Complex is high spin, that means pairing

of electrons will not take place prior to

hybridisation. Electronic configuration would

remain the same as in the free state shown

above.