Selective Four‐Electron Reduction of Oxygen by a Nonheme Heterobimetallic CuFe Complex

Abstract

We report herein the first nonheme CuFe oxygen reduction catalyst ([CuII(bpbp)(μ‐OAc)2FeIII]2+, CuFe−OAc), which serves as a functional model of cytochrome c oxidase and can catalyze oxygen reduction to water with a turnover frequency of 2.4×103 s−1 and selectivity of 96.0 % in the presence of Et3NH+. This performance significantly outcompetes its homobimetallic analogues (2.7 s−1 of CuCu−OAc with %H2O2 selectivity of 98.9 %, and inactive of FeFe−OAc) under the same conditions. Structure‐activity relationship studies, in combination with density functional theory calculation, show that the CuFe center efficiently mediates O−O bond cleavage via a CuII(μ‐η1 : η2‐O2)FeIII peroxo intermediate in which the peroxo ligand possesses distinctive coordinating and electronic character. Our work sheds light on the nature of Cu/Fe heterobimetallic cooperation in oxygen reduction catalysis and demonstrates the potential of this synergistic effect in the design of nonheme oxygen reduction catalysts.