where g is the observed g-factor, k is the spin–orbit coupling constant (178 cm 1 for Co 2+) and D is the energy differen ce betwee n 4T1g(F) ? 4T2g(F). Generally, the k0 value lies between 05 and 10,the limits of pure covalent and pure ionic bonding respectivel y.The calculate d k0 value is 085 which indicates that the bonding between the Co 2+ ions and the ligands is moderately covalent nature.