Mixed-ligand aroylhydrazone complexes of molybdenum: Synthesis, structure and biological activity

The reaction of the benzoylhydrazone of 2-hydroxybenzaldehyde (H2L) with [MoO2(acac)2] proceeds smoothly in refluxing ethanol to afford an orange complex [MoO2L(C2H5OH)] (1). The substrate binding capacity of 1 has been demonstrated by the formation and isolation of two mononuclear [MoO2L(Q)] {where Q = imidazole (2a) and 1-methylimidazole (2b)} and one dinuclear [(MoO2L)2(Q)] {Q = 4,4′-bipyridine (3)} mixed-ligand oxomolybdenum complex. All the complexes have been characterized by elemental analysis, magnetic and spectroscopic (IR, UV–Vis and NMR) measurements. The molecular structures of all the oxomolybdenum(VI) complexes (1, 2a, 2b and 3) have been determined by X-ray crystallography. In each complex, the dianionic planar ligand is coordinated to the metal centre via one enolate oxygen, one phenolate oxygen and an azomethine nitrogen atom. The complexes have been screened for their antibacterial activity against Escherichia coli, Bacillus and Pseudomonas aeruginosa. The minimum inhibitory concentration of these complexes and their antibacterial activity indicates that compounds 2a and 2b are potential lead molecules for drug designing.

The reaction of the benzoylhydrazone of 2-hydroxybenzaldehyde (H2L) with [MoO2(acac)2] proceeds smoothly in refluxing ethanol to afford an orange complex [MoO2L(C2H5OH)] (1). The coordinated ethanol ligand of 1 is found to act as a substrate-binding site, and mixed-ligand six-coordinate adducts, like [MoO2L(Imz)] (2a), [MoO2L(1-MeImz)] (2b) and [(MoO2L)2(μ-4,4′-bipy)] (3), are easily formed by the attachment of imidazole, 1-methylimidazole and 4,4′-bipyridine to this position as a co-ligand, respectively. The molecular structures of all the oxomolybdenum(VI) complexes (1, 2a, 2b and 3) have been determined by X-ray crystallography. The complexes have been screened for their antibacterial activity against Escherichia coli, Bacillus and Pseudomonas aeruginosa.Figure optionsDownload as PowerPoint slideHighlights
► Mixed-ligand aroylhydrazone complexes.
► Mono- and dinuclear oxomolybdenum(VI) complexes.
► X-ray crystal structure.
► Antibacterial activity.