Reactivity and X-ray structure of a new water-soluble manganese–salen complex

The oxidation of sulfides constitutes an important target reaction since the expected oxidation products, sulfoxides and sulfones first constitute interesting intermediates in synthetic organic chemistry and, second play an important role in medicine and toxicology, sulfoxide metabolites being responsible for the direct toxicity of sulfides. On the other hand, the development of catalytic reactions in aqueous medium constitutes a huge challenge within the overall context of eco-compatible chemistry. We describe here the synthesis and characterization of a new water-soluble manganese–salen complex, Mn(III)-N,N′-ethylenebis(2-hydroxybenzylimine)-5,5′-dicarboxylic acid or 1-Mn that was synthesized by a typical procedure. The crystal structure of this manganese complex was determined by X-ray diffraction analysis, and its catalytic properties for the oxidation of sulfides were studied. After optimization, 1-Mn appeared to be an efficient and robust catalyst for the chemoselective oxidation of thioanisole by hydrogen peroxide in aqueous medium, leading to the corresponding sulfoxide as a major product with high yields.