Synthesis, spectral, and biological studies of some metal(II) complexes with benzil salicylaldehyde acyldihydrazones

Abstract

Complexes of the general formula [M(Bsodh)]Cl and [M(Bsmdh)]Cl, where M = Co(II), Ni(II), Cu(II), Zn(II,) and Cd(II) (HBsodh = benzil salicylaldehyde oxalic acid dihydrazone and HBsmdh = benzil salicylaldehyde malonic acid dihydrazone) were synthesized and characterized by elemental analyses, molar conductance, magnetic moments, electronic, ESR, infrared spectra, and X-ray diffraction studies. The complexes are stable solids insoluble in common organic solvents and 1: 1 electrolytes. The magnetic moments and electronic spectra reveal a square-planar geometry for [M(Bsodh)]Cl and a six-coordinate octahedral geometry for [M(Bsmdh)]Cl. The HBsodh ligand bonds to the metal ion via one >C=O, two >C=N−, and one deprotonated phenolate group, whereas HBsmdh bonds through three >C=O, two >C=N−, and one phenolate group. The lattice parameters for [Co(Bsodh)]Cl and [Ni(Bsmdh)]Cl correspond to tetragonal and orthorhombic crystal lattices, respectively. ESR spectral data indicate the presence of an unpaired electron in $d_{x^2 - y^2 }$ of the Cu²⁺ ion. The ligands, as well as their metal complexes, show significant antibacterial activity against Bacillus subtilis and Pseudomonas fluorescens.