In octahedral complexes having co-ordination number 6, the degeneracy of the d-orbitals of central atom is removed due to ligand electron metal electron repulsions. In the octahedral complex three orbitals have lower energy, t_(2g) set and two orbitals have higher energy, eg set. This phenomenon is formed as crystal field splitting and the energy seperation is denoted by Delta_(0). Thus the energy of the two eg orbitals will increase by (3//5)Delta_(0) and that of the three t_(2g) will decrease by (2//5)Delta_(0). The erystal field splitling, Delta_(0) depends upon the field produced by the ligand and charge on the metal ion. Some ligands are able to produce strong field and in these cases, the splitting will be large whereas other produce weak fields and consequently result in small splitting of d-orbitals. If Delta_(0)ltP, the correct electronic configuration of d^(4) system will be