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

Abstract

The dinuclear Mn complex (Et 3NH) 2[TPA 2Mn 2(μ-Cl) 2](ClO 4) 4 ( I) was synthesized and characterized. Complex I was obtained from the reaction between MnCl 2 and [H 3TPA](ClO 4) 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 [Mn 2(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 H 2O 2 dismutation was measured for complex I and compared with other related complexes. Kinetic parameters of H 2O 2 dismutation were obtained and a possible catalytic mechanism of complex I, related to chloride-inhibited Mn catalase, was suggested.