Evidence for Cooperativity in the Disproportionation of H2O2 Efficiently Catalyzed by a Tetranuclear Manganese Complex

The base sets the rhythm for a mixed-valence MnIII(MnIV)3 complex which catalyzes the disproportionation of hydrogen peroxide. The presence of the base 1,4,7-trimethyl-1,4,7-triazacyclononane switches the catalysis kinetics from Michaelis–Menten type (Hill coefficient n=1.03) to cooperative (Hill coefficient n=1.58; see the figure). The cooperative catalytic behavior has the highest turnover constant reported to date for any synthetic manganese complex.