High Turnover Catalase Activity of a Mixed-Valence MnIIMnIII Complex with Terminal Carboxylate Donors.

The neutral dimanganese(II,III) complex [Mn2(BCPMP)(OAc)2] [ 1; BCPMP3- = 2,6-bis({(carboxymethyl)[(1-pyridyl)methyl]amino}methyl)-4-methylphenolato] has been synthesized and characterized. The complex contains two terminal carboxylate donors. Complex 1 was found to be an effective catalyst for the disproportionation of H2O2 with high catalytic rate and a turnover number of 7500, the highest turnover reported to date for a catalase mimic. The rates and TON were significantly higher than recorded for a dicationic dimanganese(II,III) counterpart ([Mn2(BPBP)(OAc)2] ·(ClO4)2, 2; BPBP- = 2,6-bis{[bis(2-pyridylmethyl)amino]methyl}-4-butylphenolato), which lacks the terminal carboxylate donors, suggesting that introduction of a terminal carboxylate donor improves activity. A well-resolved 16-line pattern obtained upon addition of H2O2 to complex 1 suggests involvement of an MnIIIMnIV species in the catalytic cycle. [ABSTRACT FROM AUTHOR]