i) Crystal field splitting: It is the splitting of the degenerate energy levels due to the presence of ligands. When ligand approaches a transition metal ion, the degenerate d-orbitals split into two sets, one with lower energy and the other with higher energy. This is known as crystal field splitting and the difference between the lower energy set and higher energy set is known as crystal field splitting energy (CFSE) Example : 3d5 of Mn2+ (ii) Linkage isomerism: When more than one atom in an ambidentate ligand is linked with central metal ion to form two types of complexes, then the formed isomers are called linkage isomers and the phenomenon is called linkage isomerism. [Cr(H2O)5(NCS)]2+ Pentaaquathiocyanate chromium (III) ion [Cr(H2O)5(NCS)]2+ Pentaaquaisothiocyanate chromium (III) ion (iii) Ambidentate ligand: The monodentate ligands with more than one coordinating atoms is known as ambidentate ligand. Monodentate ligands have only one atom capable of binding to a central metal atom or ion. For example, the nitrate ion NO2– can bind to the central metal atom/ion at either the nitrogen atom or one of the oxygen atoms. Example : — SCN thiocyanate, — NCS isothiocyanate