Question

When does coordination compounds show coordination isomerism? Explain with suitable examples.

Answer 1

Coordination isomerism happens when a coordination compound has two metal ions, and the ligands are arranged differently around these metal ions. In simple terms, the ligands are exchanged between the two metal ions, resulting in different isomers that have the same molecular formula but different structures.

1. [Co(NH₃)₆][Cr(C₂O₄)₃] and [Co(C₂O₄)₃][Cr(NH₃)₆]
   Both complexes have the same molecular formula [Co(NH₃)₆][Cr(C₂O₄)₃] but the ligands are distributed differently between the two metal centers, resulting in two distinct coordination isomers.
2. [NiCl₃(en)] and [Ni(en)₃]Cl₃
   Although both complexes have the same molecular formula, they differ in the way the ligands are distributed between the metal ion and the counterions, leading to different coordination isomers.