Spectral and Electrochemical Features of some substituted Bis(2-hydroxyaryloximato)Co(II), Ni(II), Pd(II), and Cu(II) Chelates. Crystal and Molecular Structure of Trans-bis(propanone,1-[2-hydroxyphenyl]-oximato)Ni(II)

The reaction products of five 2-hydroxyaryloximes with Ni(II), Pd(II), and Co(II) have been obtained and characterized by elemental analyses, conductometric measurements, magnetic moment determination, and spectroscopic methods (IR, ¹H NMR, electronic absorption in solutions and in solid state). Cyclic voltammetry on mercury and carbon fibre electrodes has been employed to investigate the electrochemical behaviour in DMF solutions. The effect of substituents on the structure of the chelates and the electron distribution is assessed, discussed and compared with the behaviour of the corresponding copper(II) chelates. The structure of the title compound trans-bis(propanone, 1-2-hydroxyphenyl]-oximato) nickel(II), Ni(C₉H₁₀NO₂)₂ was determined by X-ray diffraction monoclinic system (space group P2₁/n), a = 11.894, b = 5.126, c = 13.668 Å, b? = 103.72°, Z = 2. The structure was refined by full-matrix least squares to a conventional R = 0.03. Ni is on the equatorial plane and surrounded by two nitrogen and two oxygen at distances 1.884(3) Å and 1.825(2) Å, respectively.