Question

List various types of isomerism possible for coordination compounds, giving an example of each.

Answer 1

(a) Geometric isomerism:

This type of isomerism is common in heteroleptic complexes It arises dire to the different possible geometric arrangements of the ligands.
For Example

(b) Optical isomerism:

This type of isomerism arises in chiral molecules Isomers are mirror images of each other and are non-superimposable.

(c) Linkage isomerism:

This type of isomerism is found in complexes that contain ambidentate ligands.
For example:
[CO (NH₃)₅ (NO₂)]Cl₂ and
[CO (NH₃)₅ (ONO)] Cl₂

(d) Coordination isomerism:

This type of isomerism arises when the ligands are inter changed between cationic and anionic entities of different metal ions present in the complex.
[CO (NH₃)₆] [Cr (CN)₆] and
[CO (CN)₆][Cr (CN)₆]

(e) Ionisation isomerism:

This type of isomerism arises when a counter ion replaces a ligand within the coordination sphere. Thus, complexes that have the same composition, but furnish different ions when dissolved in water are called ionisation isomers.
For example