Abstract
We investigate the mechanism of water oxidation catalyzed by the CuII(pyalk)2 complex, combining density functional theory with experimental measurements of turnover frequencies, UV-visible spectra, H/D kinetic isotope effects (KIEs), electrochemical analysis, and synthesis of a derivative complex. We find that only in the cis form does CuII(pyalk)2 convert water to dioxygen. In a series of alternating chemical and electrochemical steps, the catalyst is activated to form a metal oxyl radical species that undergoes a water-nucleophilic attack defining the rate-limiting step of the reaction. The experimental H/D KIE (3.4) is in agreement with the calculated value (3.7), shown to be determined by deprotonation of the substrate nucleophile upon O-O bond formation. The reported mechanistic findings are particularly valuable for rational design of complexes inspired by CuII(pyalk)2.
Original language | English |
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Pages (from-to) | 7952-7960 |
Number of pages | 9 |
Journal | ACS Catalysis |
Volume | 8 |
Issue number | 9 |
DOIs | |
Publication status | Published - Sep 7 2018 |
Keywords
- catalysis
- copper
- density functional theory
- electrocatalysis
- water oxidation
- water-nucleophilic attack
ASJC Scopus subject areas
- Catalysis
- Chemistry(all)