Dinuclear Mn complexes as functional models of Mn catalase

Abstract

Abstract : p-Phenoxo-bis(p-carboxy1ato)dimanganese complexes with a core structure of Cs symmetry show a high catalytic activity to disproportionate H202 (2H202 + 2 H 2 0 + 02), whereas complexes with a core structure of C2 symmetry and mononuclear Mn complexes show only a low activity. For the Cs symmetric complexes, a dinuclear cis-{ MnIV(=O)]2 intermediate has been detected in the H202 disproportionation reaction and a mechanistic scheme to catalyze the H202 disproportionation through the interconversion cis-{ MnIV(=O)]~cis-{ MnIII(OH)]2 is proposed. It is shown that the equivalence of two Mn ions in electronic nature is essential to show a CAT-like activity