Question

Illustrate:

Linkage isomerism in coordination compounds.

Answer 1

1. Linkage isomerism is a type of isomerism found in coordination compounds.
2. It occurs when a ligand can bind to the central metal atom through two different donor atoms.
3. Ligands that show this behaviour are called ambidentate ligands.
4. Ambidentate ligands have two donor atoms but can coordinate through only one at a time.
5. Depending on which donor atom is involved, different isomers are formed.
6. For example, the nitrite ion \[\ce{NO^-_2}\] can coordinate to the metal either through the nitrogen atom (as –NO₂) or through the oxygen atom (as –ONO).
7. The complexes [Co(NH₃)₅(NO₂)]Cl₂ and [Co(NH₃)₅(ONO)]Cl₂ are linkage isomers.
8. In the first, \[\ce{NO^-_2}\] is bonded through nitrogen; in the second, it is bonded through oxygen.
9. These isomers have the same molecular formula but different bonding modes, leading to different properties.