Antibacterial activities and spectroscopic characterization of synthetic metal complexes of 4-(3-(hydroxyimino)-4-oxopentan-2-ylidene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

A new series of manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) mercury(II) strontium(II), chromium(III), iron(III) and zirconyl(II) complexes of 4-3-(hydroxyimino)-4-oxopentan-2-ylidene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one(HL) have been prepared and characterized by elemental and thermal (TG) analyses, IR, UV-VIS, ¹H-NMR, ESR and mass spectra as well as magnetic susceptibilities and conductivities measurements. Molar conductance in DMSO solvent indicated that, all complexes are nonelectrolytes except complexes (3), (10), (11) and (15) are electrolyte. The spectral data showed that, the ligand behaved either as neutral tridentate, as in complexes (3), (4), (5), (13) and (15), monobasic tridentate, as in complexes (2), (6), (8–12) and (14) or monobasic tetradentate ligand, as in complex (7), bonding to the metal ions through the nitrogen atom of the protonated or deprotonated oxime group, carbonyl oxygen atom of antipyrine moiety and azomethine group nitrogen atom $\upsilon$ (C = N)_imine or oxamato oxygen atom forming rings including the metal ion. The electronic spectra showed that, the complexes are distorted octahedral geometry. The ESR spectra of solid copper(II) complexes (2) showed g $_{\Vert}$ > g $_{\bot}$ > g_e, indicating distorted octahedral structure and the presence of the unpaired electron in a d_(x2-y2) orbital with significant mixed covalent or ionic bond character, however, copper(II), complex (3) showed isotropic spectrum. The antibacterial activities of the ligand and its complexes against Escherichia coli, Bacillus subtitles which studied by disk diffusion method indicated that, some complexes are more active than the free ligand.