Synthesis and characterization of nickel(II), zinc(II), copper(II), cobalt(II) and cobalt(III) complexes of alpha-dicarbonylbis(aroylhydrazone)

A variety of alpha-dicarbonylbis(aroylhydrazone) H2L (1) ligands were synthesized and used to synthesize complexes formulated as NiL . nH(2)O, Zn2L2 . nH(2)O, CuL, CoL . nH(2)O and Na[CoL(NO2)(2)], where L refers to the dinegative anion of alpha-dicarbonylbis(aroylhydrazone) ligand. These complexes were investigated by elemental analyses, IR and UV-vis spectra and, for zinc(II), Na[CoL(NO2)(2)] and the anhydrous NiL complexes, H-1 NMR spectra were measured in order to elucidate their structures. Other octahedral complexes such as Ni(H2L)(2)(OAc)(2) and Co(HL) . nH(2)O were isolated and characterized. Different modes of coordination were assigned to the ligand 1 and its anions in the isolated complexes; dinegative tetradentate, mononegative bidentate and neutral bidentate. (C) 1997 Elsevier Science Ltd.