Synthesis and Characterization of Co(II), Ni(II), Cu(II) and Zn(II) Complexes with an ONO- and an NNO-Functionalized Ligand

Abstract

A new ligand was synthesized from condensation of 2-aminophenol and 2-acetylbenzimidazole. This ligand (HAPAB, 6) was characterized based on elemental analysis, IR, 1H-NMR and 13C-NMR and MS spectral spectra. The complexes of the ligands, HAPAB (6) and 2-acetylfruan benzoylhydrazone (HAFBH, 3), with Co(II), Ni(II), Cu(II) and Zn(II), encoded a-d, were prepared by reaction of their methanolic acetate salts with the ligands in methanol in 1:2 metal to ligand mole ratio. These complexes, M(II)L2, 7a-d and 8a-d, were similarly characterized based on their physicochemical data by elemental analysis, IR, 1H-NMR and 13C-NMR, MS, molar conductance and electronic absorption spectra. The complexes consist of two ligands that give six coordinate bonding to each metal ion on a meridional plane through binding with the acetylfuran-O, the azomethine-N and the oxygen donor atom in the enol form of the hydrazone 3 and the 2-acetylbenzimidazole-N, the azomethine-N, and the phenoxo-O atoms of the imine 6 respectively. The ligands function as monobasic ONO- and NNO-trifunctional donor ligands where the deprotonated enolic form is preferred in the coordination producing distorted octahedral complexes. Key words: metal (II) complexes, Schiff bases, NNO-tridentate ligand, ONO-tridentate ligand