Coordination Isomerism occurs in salts where both the cation and anion are coordination complexes.

• It arises from the interchange of ligands between the cationic and anionic metal centers.
• In the first salt, $N{H}_3$ is with $Co$ and $CN$ is with $Cr$.
• In its isomer, $N{H}_3$ is with $Cr$ and $CN$ is with $Co$.
• They share the same empirical formula but have different identities of the complex ions.