Evidence of two-state reactivity in water oxidation catalyzed by polyoxometalate-based complex [Mn3(H2O)3(SbW9O33)2]12−

Abstract

In this work, the key OO bond formation step in water oxidation catalyzed by a polyoxometalate-based complex [Mn3(H2O)3(SbW9O33)2]12− was theoretically investigated. The MnV-oxo species rather than MnIV-oxo species, is computed to be responsible for OO bond formation via water nucleophilic attack mechanism. During OO bond formation based on MnV-oxo species, two-state reactivity is found and the energy profile switches from the 13et state to the 15et state through a minimum energy crossing point, which significantly reduces the activation barrier. The observed spin inversion phenomenon in OO bond formation is attributed to the exchange-enhanced reactivity for 15et state, but not for 13et state.