Synthesis, spectral characterization and electrochemical investigations of mononuclear Cu (II), Ni (II) and Co (II) metal complexes containing different new vic-dioxime groups

Three new vic-dioxime: N-(2-methyl-2-butylamine)-anti-p-tolylglyoxime (L1H2), N-(4-amino-2,2,6,6-tetramethylpiperidine)-anti-p-tolylglyoxime (L2H2) and N,N'-(4-amino-2,2,6,6-tetramethylpiperidine)-anti-glyoxime (L3H2) were prepared by the reaction of anti-p-tolylchloroglyoxime and anti-dichloroglyoxime with 2-methyl-2-butylamine and 4-amino-2,2,6,6-tetramethylpiperidine in absolute THF at -15C. Mononuclear metal complexes with a metal-ligand ratio of 1:2 were prepared using Cu(II), Ni(II) and Co(II) salts. FT-IR spectra show that the ligands act in a tetradentate manner and coordinates N4 donor groups of ligands to Cu(II), Ni(II) and Co(II) ions. The Cu(II) complexes of these ligands are proposed to be square-planar; the Ni(II) and Co(II) complexes are proposed to be octahedral with two water molecules as axial ligands. The ligands and their metal complexes were characterized by elemental analyses, Ft-IR, UV-Vis, ¹H and ¹³C-NMR spectra, magnetic susceptibility measurements and cyclic voltammetry. The electrochemical behavior of the Ni(II), Co(II) and Cu(II) complexes was investigated by cyclic voltammetry in DMSO as well.