Synthesis and structural characterization of a new high-valent bis(oxo)-bridged manganese(IV) complex and its catechol oxidase activity

Abstract

The work in this report presents the synthesis, structural and spectroscopic characterization of a new type of high-valent bis(oxo)-bridged dimanganese(IV) complex 1 supported by a pyridine and phenol based tetradentate flexible N3O donor HL ligand (where HL=2-benzyl-6-((bis(pyridin-2-ylmethyl)amino)methyl)-4-chlorophenol). Complex 1 possess unique Mn2(μ-O)2 core with short Mn⋯Mn distances (2.65Å) and Mn–O distance (1.80Å). This dinuclear manganese(IV) complex show excellent catecholase-like activity for the aerobic oxidation of 3,5-di-tert-butylcatechol to the corresponding o-quinone in acetonitrile at 25°C. Kinetic measurements suggest that the rate of catechol oxidation follows saturation kinetics with respect to the substrate and first order kinetics with respect to the catalyst.