Computational studies were carried out on three Zn(II) and three Ni(II) complexes, namely [NiL1(phen)(2)], [ZnL1(phen)(2)], [NiL2(phen)(2)], [ZnL2(phen)(2)], [NiL3(phen)(2)] and [ZnL3(phen)(2)]. These complexes were synthesized in 2014 by Raman and Mahalalcshmi. Optimized structures of the studied complexes were calculated. IR and UV Vis spectra were calculated and examined in detail. Additionally, non-linear optical (NLO) properties and natural electron configurations of the metal atoms were investigated 'using some quantum chemical parameters and natural bond orbital (NBO) analysis. (C) 2015 Elsevier Ltd. All rights reserved.