Linkage Isomerism is the existance of co-ordination compounds that have the same atomic composition differing with the attachment arrangement to the central atom of a ligand group. Typical ligands that give rise to linkage isomers are:

• thiocyanate, SCN^-
• selenocyanate, SeCN^-
• nitrite, NO₂^-
• sulfite, SO₃^2-

Examples of linkage isomers are violet-colored and orange-colored [(NH₃)₅Co-NCS²⁺. The isomerization of the S-bonded isomer to the N-bonded isomer occurs intramolecularly.

Buckingham, D. A.; Creaser, I. I.; Sargeson, A. M. "Mechanism of Base Hydrolysis for Co^III(NH₃)₅X²⁺ Ions. Hydrolysis and Rearrangement for the Sulfur-Bonded Co(NH₃)₅SCN²⁺ Ion" Inorganic Chemistry (1970), 9(3), 655-61.