Water-Nucleophilic Attack Mechanism for the CuII(pyalk)2 Water-Oxidation Catalyst

Benjamin Rudshteyn, Katherine J. Fisher, Hannah M.C. Lant, Ke R. Yang, Brandon Q. Mercado, Gary W. Brudvig, Robert H. Crabtree, Victor S. Batista

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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 languageEnglish
Pages (from-to)7952-7960
Number of pages9
JournalACS Catalysis
Volume8
Issue number9
DOIs
Publication statusPublished - Sep 7 2018

Keywords

  • catalysis
  • copper
  • density functional theory
  • electrocatalysis
  • water oxidation
  • water-nucleophilic attack

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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    Rudshteyn, B., Fisher, K. J., Lant, H. M. C., Yang, K. R., Mercado, B. Q., Brudvig, G. W., Crabtree, R. H., & Batista, V. S. (2018). Water-Nucleophilic Attack Mechanism for the CuII(pyalk)2 Water-Oxidation Catalyst. ACS Catalysis, 8(9), 7952-7960. https://doi.org/10.1021/acscatal.8b02466