Synthesis, spectroscopic and biological studies of metal complexes of an ONO donor pyrazolylhydrazone – Crystal structure of ligand and Co(II) complex

Abstract

A new pyrazolylhydrazone, 2-(2-(1,5-dimethy-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazolyl-4-yl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione (HL) and its Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes were synthesized and structurally characterized by elemental analysis, molar conductance, magnetic measurements and spectral (IR, 1H NMR, UV–vis, HRMS) measurements. All complexes possess ML2 stoichiometry with L behaving as monoanionic tridentate ONO donor. Single crystal X-ray diffraction reveals that HL and CoL2 crystallize in orthorhombic system with Pbcn space group. Hydrogen bonding interactions between molecules of CoL2 results in the formation of an infinite zig-zag chain extending along the ‘b’ axis. EPR spectrum of Cu(II) complex at 77 K suggests mononuclear and distorted octahedral geometry for [CuL2]. Antimicrobial activity of HL and its complexes were investigated and minimum inhibitory concentrations identified. Bacterial and fungal organisms used were gram-positive Staphylococcus aureus, gram-negative Escherichia coli, Aspergillus niger and Candida albicans.