Water nucleophilic attack (WNA) on high-valent terminal Mn-oxo species is proposed for O-O bond formation in natural and artificial water oxidation. Herein, we report an electrocatalytic water oxidation reaction with MnIIItris(pentafluorophenyl)corrole (1) in propylene carbonate (PC). O2was generated at the MnV/IVpotential with hydroxide, but a more anodic potential was required to evolve O2with only water. With a synthetic MnV(O) complex of 1 , a second-order rate constant,k2(OH-), of 7.4 × 103M-1s-1was determined in the reaction of the MnV(O) complex of 1 with hydroxide, whereas its reaction with water occurred much more slowly with ak2(H2O) value of 4.4 × 10-3M-1s-1. This large reactivity difference of MnV(O) with hydroxide and water is consistent with different electrocatalytic behaviors of 1 with these two substrates. Significantly, during the electrolysis of 1 with water, a MnIV-peroxo species was identified with various spectroscopic methods, including UV-vis, electron paramagnetic resonance, and infrared spectroscopy. Isotope-labeling experiments confirmed that both O atoms of this peroxo species are derived from water, suggesting the involvement of the WNA mechanism in water oxidation by a Mn complex.
Bibliographical noteFunding Information:
We are grateful for support from the Fok Ying-Tong Education Foundation for Outstanding Young Teachers in University, the National Natural Science Foundation of China (21573139 and 21773146), the Fundamental Research Funds for the Central Universities (GK202103045 and GK202003037), the Research Funds of Shaanxi Normal University, China Postdoctoral Science Foundation (2019M663614), the NRF of Korea (NRF-2021R1A3B1076539 to W.N. and NRF-2020R1I1A1A01074630 to Y.-M.L.), and the MEXT (Japan, 16H02268 to S.F.).
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