A simple example is provided by complexes
containing the thiocyanate ligand, NCS
–, which may bind through the
nitrogen to give M–NCS or through sulphur to give M–SCN Jørgensen
discovered such behaviour in the complex [Co(NH3)5(NO2)]Cl2, which is
obtained as the red form, in which the nitrite ligand is bound through
oxygen (–ONO), and as the yellow form, in which the nitrite ligand is
bound through nitrogen (–NO2) This type of isomerism arises from the interchange of ligands between
cationic and anionic entities of different metal ions present in a complex An example is provided by [Co(NH3)6][Cr(CN)6], in which the NH3 ligands
are bound to Co
3+ and the CN
– ligands to Cr
3+