Electrochemical reductions of Ni2+, Cu2+ and Zn2+ complexes of azinyl methyl ketoximes on mercury

Electroreductions of Ni2+, Cu2+ and Zn2+ complexes of azinyl (pyridin-2-yl, pyridazin-3-yl, pyrimidin-2-yl, pyrimidin-4-yl, pyrazinyl) methyl ketoxime s on mercury electrode were studied using de polarography. Three different types of complex behavior on the mercury electrode were observed: In the Ni 2+ complexes, the hydroxyimino group of the ligand is reduced, whereas in t he Cu2+ complexes, the reduction proceeds on the metal ion. With Zn2+ compl ex of methyl pyridin-2-yl ketoxime, only reduction waves of the uncoordinat ed ligand and metal were observed due to a rapid decomplexation pre-equilib rium. The structure of [Zn(methyl pyridin-2-yl ketoxime)(2)(NO3)(2)], isola ted from water-ethanolic solution, was determined by X-ray diffraction. The distorted octahedral coordination sphere around the zinc atom, made up of two pyridine and two oxime nitrogen atoms and two nitrate oxygen atoms, was verified.