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

doi:10.1021/acscatal.8b02466

Water-Nucleophilic Attack Mechanism for the Cu^II(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

Yale University

Research output: Contribution to journal › Article › peer-review

17 Citations (Scopus)

Abstract

We investigate the mechanism of water oxidation catalyzed by the Cu^II(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 Cu^II(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 Cu^II(pyalk)₂.

Original language	English
Pages (from-to)	7952-7960
Number of pages	9
Journal	ACS Catalysis
Volume	8
Issue number	9
DOIs	https://doi.org/10.1021/acscatal.8b02466
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)

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@article{50f4bd710f2f4760983ddbc23d223512,

title = "Water-Nucleophilic Attack Mechanism for the CuII(pyalk)2 Water-Oxidation Catalyst",

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.",

keywords = "catalysis, copper, density functional theory, electrocatalysis, water oxidation, water-nucleophilic attack",

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

note = "Funding Information: V.S.B., R.H.C., and G.W.B. acknowledge financial support as a part of the Argonne−Northwestern Solar Energy Research (ANSER) Center of the federally funded Energy Frontier Research Center (Award Number DE-SC0001059). V.S.B. acknowledges high-performance computing time from NERSC, from DOD Copper, and from the Center for Research Computing at Yale University. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number ACI-1053575. B.R. and K.J.F. gratefully acknowledge support from the NSF Graduate Research Fellowship under Grant No. DGE-1122492. B.R. thanks the Energy Sciences Institute members, particularly Dr. Svante Hedstr{\"o}m, Dr. Atanu Acharya, and Dr. Uriel Morzan, for helpful comments.",

year = "2018",

month = sep,

day = "7",

doi = "10.1021/acscatal.8b02466",

language = "English",

volume = "8",

pages = "7952--7960",

journal = "ACS Catalysis",

issn = "2155-5435",

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T1 - Water-Nucleophilic Attack Mechanism for the CuII(pyalk)2 Water-Oxidation Catalyst

AU - Rudshteyn, Benjamin

AU - Fisher, Katherine J.

AU - Lant, Hannah M.C.

AU - Yang, Ke R.

AU - Mercado, Brandon Q.

AU - Brudvig, Gary W.

AU - Crabtree, Robert H.

AU - Batista, Victor S.

N1 - Funding Information: V.S.B., R.H.C., and G.W.B. acknowledge financial support as a part of the Argonne−Northwestern Solar Energy Research (ANSER) Center of the federally funded Energy Frontier Research Center (Award Number DE-SC0001059). V.S.B. acknowledges high-performance computing time from NERSC, from DOD Copper, and from the Center for Research Computing at Yale University. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number ACI-1053575. B.R. and K.J.F. gratefully acknowledge support from the NSF Graduate Research Fellowship under Grant No. DGE-1122492. B.R. thanks the Energy Sciences Institute members, particularly Dr. Svante Hedström, Dr. Atanu Acharya, and Dr. Uriel Morzan, for helpful comments.

PY - 2018/9/7

Y1 - 2018/9/7

N2 - 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.

AB - 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.

KW - catalysis

KW - copper

KW - density functional theory

KW - electrocatalysis

KW - water oxidation

KW - water-nucleophilic attack

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