Synthesis, structure and catalase activity of the [TPA2Mn2(μ-Cl)2]2+ complex

Abstract

The dinuclear Mn complex (Et3NH)2[TPA2Mn2(μ-Cl)2](ClO4)4 (I) was synthesized and characterized. Complex I was obtained from the reaction between MnCl2 and [H3TPA](ClO4)3 in MeOH. Structural analysis of I showed the two Mn(II) atoms are bridged by two chloride ligands, forming a bis(μ-chloro)dimanganese core. The [Mn2(μ-Cl)2]2+ core, with a Mn-Mn distance of 3.521(2) Å, is similar to the active site found in chloride-inhibited Mn catalase. EPR and temperature-dependent magnetic susceptibility measurements of complex I showed an antiferromagnetic interaction between the two S = 5/2 Mn centers with an exchange parameter J = -8.8 cm-1. Catalytic activity of H2O2 dismutation was measured for complex I and compared with other related complexes. Kinetic parameters of H2O2 dismutation were obtained and a possible catalytic mechanism of complex I, related to chloride-inhibited Mn catalase, was suggested. © 2007 Elsevier Ltd. All rights reserved.