DFT Study on the Mechanism of Water Oxidation Catalyzed by a Mononuclear Copper Complex

This work employed DFT calculations to elucidate the mechanism of water oxidation reaction catalyzed by a mononuclear pyridine-based copper complex, which was reported to be a homogeneous water oxidation catalyst in a pH=11.84 buffer solution. The coordination of one water molecule with the Cu^ II center leads to the generation of the Cu^ II- OH₂ (1- H₂ O). The active species ( Cu^ IV= O, 3) is generated after two subsequent proton-coupled electron transfer processes from 1- H₂ O. $3$ triggers the O-O bond formation via water nucleophilic attack mechanism. The triplet O₂ can be released after following two oxidation processes. The formation of the O-O bond is the rate-determining step for the catalytic cycle associated with a total barrier of 19.3 kcal/mol.