H2 Oxidation Electrocatalysis Enabled by Metal-to-Metal Hydrogen Atom Transfer

A Homolytic Approach to a Heterolytic Reaction

Geoffrey M. Chambers, Eric Wiedner, R Morris Bullock

Research output: Contribution to journalArticle

Abstract

Oxidation of H2 in a fuel cell converts the chemical energy of the H−H bond into electricity. Electrocatalytic oxidation of H2 by molecular catalysts typically requires one metal to perform multiple chemical steps: bind H2, heterolytically cleave H2, and then undergo two oxidation and two deprotonation steps. The electrocatalytic oxidation of H2 by a cooperative system using Cp*Cr(CO)3H and [Fe(diphosphine)(CO)3]+ has now been invetigated. A key step of the proposed mechanism is a rarely observed metal-to-metal hydrogen atom transfer from the Cr−H complex to the Fe, forming an Fe−H complex that is deprotonated and then oxidized electrochemically. This “division of chemical labor” features Cr interacting with H2 to cleave the H−H bond, while Fe interfaces with the electrode. Neither metal is required to heterolytically cleave H2, so this system provides a very unusual example of a homolytic reaction being a key step in a molecular electrocatalytic process.

Original languageEnglish
Pages (from-to)13523-13527
Number of pages5
JournalAngewandte Chemie - International Edition
Volume57
Issue number41
DOIs
Publication statusPublished - Oct 8 2018

Fingerprint

Electrocatalysis
Hydrogen
Metals
Atoms
Oxidation
Carbon Monoxide
Deprotonation
Fuel cells
Electricity
Personnel
Electrodes
Catalysts

Keywords

  • electrocatalysis
  • homolytic cleavage
  • hydrides
  • hydrogen atom transfer
  • proton transfer

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

Cite this

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title = "H2 Oxidation Electrocatalysis Enabled by Metal-to-Metal Hydrogen Atom Transfer: A Homolytic Approach to a Heterolytic Reaction",
abstract = "Oxidation of H2 in a fuel cell converts the chemical energy of the H−H bond into electricity. Electrocatalytic oxidation of H2 by molecular catalysts typically requires one metal to perform multiple chemical steps: bind H2, heterolytically cleave H2, and then undergo two oxidation and two deprotonation steps. The electrocatalytic oxidation of H2 by a cooperative system using Cp*Cr(CO)3H and [Fe(diphosphine)(CO)3]+ has now been invetigated. A key step of the proposed mechanism is a rarely observed metal-to-metal hydrogen atom transfer from the Cr−H complex to the Fe, forming an Fe−H complex that is deprotonated and then oxidized electrochemically. This “division of chemical labor” features Cr interacting with H2 to cleave the H−H bond, while Fe interfaces with the electrode. Neither metal is required to heterolytically cleave H2, so this system provides a very unusual example of a homolytic reaction being a key step in a molecular electrocatalytic process.",
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AU - Bullock, R Morris

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N2 - Oxidation of H2 in a fuel cell converts the chemical energy of the H−H bond into electricity. Electrocatalytic oxidation of H2 by molecular catalysts typically requires one metal to perform multiple chemical steps: bind H2, heterolytically cleave H2, and then undergo two oxidation and two deprotonation steps. The electrocatalytic oxidation of H2 by a cooperative system using Cp*Cr(CO)3H and [Fe(diphosphine)(CO)3]+ has now been invetigated. A key step of the proposed mechanism is a rarely observed metal-to-metal hydrogen atom transfer from the Cr−H complex to the Fe, forming an Fe−H complex that is deprotonated and then oxidized electrochemically. This “division of chemical labor” features Cr interacting with H2 to cleave the H−H bond, while Fe interfaces with the electrode. Neither metal is required to heterolytically cleave H2, so this system provides a very unusual example of a homolytic reaction being a key step in a molecular electrocatalytic process.

AB - Oxidation of H2 in a fuel cell converts the chemical energy of the H−H bond into electricity. Electrocatalytic oxidation of H2 by molecular catalysts typically requires one metal to perform multiple chemical steps: bind H2, heterolytically cleave H2, and then undergo two oxidation and two deprotonation steps. The electrocatalytic oxidation of H2 by a cooperative system using Cp*Cr(CO)3H and [Fe(diphosphine)(CO)3]+ has now been invetigated. A key step of the proposed mechanism is a rarely observed metal-to-metal hydrogen atom transfer from the Cr−H complex to the Fe, forming an Fe−H complex that is deprotonated and then oxidized electrochemically. This “division of chemical labor” features Cr interacting with H2 to cleave the H−H bond, while Fe interfaces with the electrode. Neither metal is required to heterolytically cleave H2, so this system provides a very unusual example of a homolytic reaction being a key step in a molecular electrocatalytic process.

KW - electrocatalysis

KW - homolytic cleavage

KW - hydrides

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KW - proton transfer

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