Electron paramagnetic resonance studies of Cu2+ ion in Tetraaqua-di(nicotinamide)Ni(II)-saccharinates single crystals

X-band (∼9.8 GHz) electron paramagnetic resonance (EPR) measurement at ambient temperature in three mutually perpendicular planes have been carried out on a single crystal of Cu2+ doped mixed ligand complex of Ni(II) with saccharin and nicotinamide [Ni(Nic)2(H2O)4](sac)2. The angular dependent spectra showed that the Cu2+ ion enters Ni2+ sites in the lattice and distorted local environment of Ni2+ site. The principal g and A values, covalency parameter (α′2), mixing coefficients (α and β) and Fermi contact term (K) have been evaluated from the EPR analysis. The ground-state wave function of the Cu2+ ion has been constructed using the α′2, α and β values. The nature of the distortion present in the lattice is obtained from the values of the mixing coefficients.