Question

What are linkage isomers? Give me an example

Answer 1

Linkage isomers are coordination compounds that have the same composition but differ in the connectivity of the ligand to the metal.

For example, a thiocyanato group could be connected to the metal atom by either the S atom or the N atom.

Typical ligands that give rise to linkage isomers are:

• thiocyanate, SCN⁻ and isothiocyanate, NCS⁻
• selenocyanate, SeCN⁻ and isoselenocyanate, NCSe⁻
• nitrite, NO₂⁻
• sulfite, SO₃²⁻

Two examples of linkage isomers are

• the violet thiocyanato-κ-S and orange thiocyanato-κ-N isomers
  [(NH₃)₅Co-SCN]²⁺ and [(NH₃)₅Co-NCS]²⁺

• the yellow nitrito-κ-N and red nitrito-κ-O isomers [(NH₃)₅Co-NO₂]²⁺ and [(NH₃)₅Co-ONO]²⁺