A cationic manganese porphyrin, MnIII-TDMImP, is an efficient, homogeneous, single-site water oxidation electrocatalyst at neutral pH. The measured turnover frequency for oxygen production is 32 s-1. Mechanistic analyses indicate that MnV(O)(OH2), the protonated form of the corresponding trans-MnV(O)2 species, is generated from the MnIII(OH2)2 precursor in a 2-e- two-proton process and is responsible for O-O bond formation with a H2O molecule. Chloride ion is a competitive substrate with H2O for the MnV(O)(OH2) oxidant, forming hypochlorous acid with a rate constant that is 3 orders of magnitude larger than that of water oxidation. The data allow the construction of an experimental energy landscape for this water oxidation catalysis process.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry