Synthesis, spectral characterization and crystal structure of copper(II) complexes of 2-benzoylpyridine-N(4)-phenylsemicarbazone

An interesting series of nine new copper(II) complexes [Cu2L2(OAc)2]·H2O (1), [CuLNCS]·½H2O (2), [CuLNO3]·½H2O (3), [Cu(HL)Cl2]·H2O (4), [Cu2(HL)2(SO4)2]·4H2O (5), [CuLClO4]·½H2O (6), [CuLBr]·2H2O (7), [CuL2]·H2O (8) and [CuLN3]·CH3OH (9) of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on the EPR studies, spin Hamiltonian and bonding parameters have been calculated. The g   values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the dx2-y2dx2-y2 orbital. The structure of the compound, [Cu2L2(OAc)2] (1a) has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed monoclinic space group P21/n. The coordination geometry about the copper(II) in 1a is distorted square pyramidal with one pyridine nitrogen atom, the imino nitrogen, enolate oxygen and acetate oxygen in the basal plane, an acetate oxygen form adjacent moiety occupies the apical position, serving as a bridge to form a centrosymmetric dimeric structure.

Graphical abstractCopper(II) complexes of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been synthesized and physico-chemically characterized. Based on the EPR studies, spin Hamiltonian and bonding parameters have been calculated. The coordination geometry about the copper(II) in a complex prepared from copper acetate is distorted square pyramidal with two acetate ions bridge to form a centrosymmetric dimeric structure.Figure optionsDownload full-size imageDownload as PowerPoint slide