Synthesis and spectral characterization of copper(II) complexes derived from 2-benzoylpyridine-N4,N4-dimethyl-3-thiosemicarbazone: Crystal structure of a binuclear complex

Six copper(II) complexes [Cu-2(L)(2)SO4]center dot H2O (1), [Cu-2(L)(2)(OAc)(2)center dot H2O (2), [Cu(L)NO3](2) (3), [Cu(L)N-3](2)center dot H2O (4), [Cu(L)NCS]center dot H2O (5) and [Cu(L)I] (6) of 2-benzoylpyridine-N-4,N-4-dimethyl-3-thiosemicarbazone (HL) were prepared and characterized using partial elemental analysis, magnetic susceptibility, conductivity measurements, FT-IR, UV-Vis and EPR studies. The molecular structure of [Cu-2(L)(2)(OAc)(2)] (2a) was resolved using single crystal X-ray diffraction studies and it was found to have distorted square pyramidal geometry with the basal plane occupied by thiosemicarbazone and the acetate oxygen O2. The compound crystallized in monoclinic space group P2(1)/n and formed a centrosymmetric dimer, bridged through oxygen of the acetate moiety. From the physicochemical studies, it was found that thiosemicarbazone coordinates through one of the pyridyl nitrogen, azomethine nitrogen and thioiminolate sulfur atoms. Binuclear nature of some of the complexes was confirmed from EPR parameters and magnetic moment values. In all complexes g values in frozen DMF, indicate the presence of the unpaired electron residing in the d(x2-y2) orbital. (C) 2014 Elsevier Ltd. All rights reserved.