c
The complexes \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]\left(\mathrm{Cr}(\mathrm{CN})_{6}\right]\) and \(\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{6}\right]\left[\mathrm{Co}(\mathrm{CN})_{6}\right]\) are the examples of coordination isomerisms. This isomerism occurs only in those complexes in which both cation and anion are complex. It occurs due to exchange of ligands between cation and anion