Electrochemical Reductions of Ni2+, Cu2+ and Zn2+ Complexes of Azinyl Methyl Ketoximes on Mercury

Abstract

Electroreductions of Ni2+, Cu2+ and Zn2+ complexes of azinyl (pyridin-2-yl, pyridazin-3-yl, pyrimidin-2-yl, pyrimidin-4-yl, pyrazinyl) methyl ketoximes on mercury electrode were studied using dc polarography. Three different types of complex behavior on the mercury electrode were observed: In the Ni2+ complexes, the hydroxyimino group of the ligand is reduced, whereas in the Cu2+ complexes, the reduction proceeds on the metal ion. With Zn2+ complex of methyl pyridin-2-yl ketoxime, only reduction waves of the uncoordinated ligand and metal were observed due to a rapid decomplexation pre-equilibrium. The structure of [Zn(methyl pyridin-2-yl ketoxime)2(NO3)2], isolated 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.