Synthesis, structural characterization, thermal and electrochemical studies of mixed ligand Cu(II) complexes containing 2-phenyl-3-(benzylamino)-1,2-dihydroquinazoline-4-(3H)-one and bidentate N-donor ligands

Some mixed ligand Cu(II) complexes of the type [Cu(L)(en)X2] (1a–3a), [Cu(L)(en)](ClO4)2 (4a), [Cu(L)(phen)X2] (1b–3b) and [Cu(L)(phen)](ClO4)2 (4b) [where L = 2-phenyl-3-(benzylamino)-1,2-dihydroquinazoline-4-(3H)-one; en = ethylenediamine; phen = 1,10-phenanthroline; X = Cl−, N3− and NCS−] have been prepared. The complexes were characterized on the basis of elemental analysis, molar conductance, magnetic moment, IR, UV–vis, mass, ESR and thermal studies. On the basis of electronic spectral data and magnetic susceptibility measurement octahedral geometry has been proposed for 1a–3a and 1b–3b and square-planer geometry for 4a and 4b. The ESR spectral data of complexes provided information about their structure on the basis of Hamiltonian parameters and degree of covalency. The electrochemical behaviour of mixed ligand Cu(II) complexes was studied which showed that complexes of phen appear at more positive potential as compared to those for corresponding en complexes.