Synthesis, structure and catalase activity of three new manganese(III) complexes with a N,N,O donor Schiff-base ligand

Three new Mn(III) complexes [Mn(L)(L′)(N3)] (1), [Mn(L)(L′)(Cl)] (2) and {[Mn(L)(L′)(H2O)](ClO4)}2 (3) (where, HL = 2-[1-(2-dimethylamino-ethylimino)-ethyl]-phenol and HL′ = o-hydroxyacetophenone) have been synthesized and characterized by UV–Vis and IR spectroscopy and single-crystal X-ray diffraction analyses. All of the three monomeric complexes show six-coordinate octahedral geometry around the Mn(III) center and are bonded to the deprotonated tridentate ligand L together with the deprotonated bidentate ligand L′ and a labile monodentate donor i.e. azide in 1, chloride in 2 and water in 3, respectively. All of the complexes catalyze the disproportionation of hydrogen peroxide into water and dioxygen i.e. they possess catalase activity. The turnover numbers of the complexes follow the order: 3 > 1 > 2.