Isomerism In Coordination Compounds

Linkage isomerism occurs in coordination compounds when the ligands can bind to the central metal atom/ion through different atoms. This typically involves ligands that contain more than one potential donor atom but only one atom can bind at a time. In the given options, we need to identify which compound demonstrates linkage isomerism.

The chloride ion, Cl⁻, involved here does not show linkage isomerism as it can only bind through a single atom.

The nitrite ion ( ) can coordinate to the metal center through the nitrogen atom to form the nitro isomer or through an oxygen atom to form the nitrito isomer. This ability to bind in two ways results in linkage isomerism.

The cyanide ion (CN⁻) typically bonds through the carbon atom and does not show linkage isomerism as it cannot bind through the nitrogen atom effectively.

Water (H₂O) acts as a ligand using oxygen and does not display linkage isomerism as it has only one donor atom.

Therefore, the compound that exhibits linkage isomerism is as it contains the nitrite ligand (NO₂⁻) which can coordinate in different ways.