Synthesis, characterization and catalytic activity of transition metal complexes with thiosemicarbazone core ligand

A series of metal complexes of Fe(II) and Zn(II) having the general composition [M(L)X₂] with benzil bis (thiosemicarbazone) has been prepared and characterized by element chemical analysis, magnetic susceptibility measurements, and spectral (FTIR) studies. The IR spectral data suggest the involvement of sulphur and azomethane nitrogen in coordination to the central metal ion. On the basis of spectral studies, complexes of Zn(II) and Fe(II) show octahedral geometry. The aromatic benzaldehyde dissolved in aqueous acetic acid, were oxidized in quantitative to good yields by 30% H₂ O₂ in presence of traces of [M(L)X₂] (substrate: catalyst ratio 85 400 to 387 500: 1). Conditions for highest yields, under most economical conditions were obtained. Higher catalyst concentrations decrease the yield. In this new, simple and economical method which is environmentally safe and requires less time, [M(L)X₂] species of Fe and Zn (II) probably catalyze the oxidation.