Synthesis,structural studies and biological activity of dioxomolybdenum(VI), dioxotungsten(VI), thorium(IV) and dioxouranium(VI) complexes with 2-hydroxy-5-methyl and 2-hydroxy-5-chloroacetophenone benzoylhydrazone

New complexes of MoO₂(VI), WO₂(VI), Th(IV) and UO₂(VI) with aroyl hydrazones have been prepared and characterized by various physicochemical methods. Elemental analysis suggested 1 : 1 metal : ligand stoichiometry for MoO₂(VI), WO₂(VI), and UO₂(VI) complexes whereas 1 : 2 for Th(VI) complexes. The physicochemical studies showed that MoO₂(VI), Th(IV) and UO₂(VI) complexes are octahedral. The electrical conductivity of these complexes lies in the range 1.00 × 10⁻⁷−3.37 × 10⁻¹¹Ω⁻¹ cm⁻¹ at 373 K. The complexes were found to be quite stable and decomposition of the complexes ended with respective metal oxide as a final product. The thermal dehydration and decomposition of these complexes were studied kinetically using both Coats-Redfern and Horowitz-Metzger methods. It was found that the thermal decomposition of the complexes follow first order kinetics. The thermodynamic parameters of the decomposition are also reported. The biological activities of ligands and their metal complexes were tested against various microorganisms.