H2 Oxidation Electrocatalysis Enabled by Metal‐to‐Metal Hydrogen Atom Transfer: A Homolytic Approach to a Heterolytic Reaction

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 deprotonat...

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Bibliographic Details
Published in:Angewandte Chemie 2018-10, Vol.130 (41), p.13711-13715
Main Authors: Chambers, Geoffrey M., Wiedner, Eric S., Bullock, R. Morris
Format: Article
Language:English
Subjects:
Bindungshomolyse
Catalysts
Chemical energy
Chemistry
Chromium
Division
Elektrokatalyse
Fuel cells
Fuel technology
Hydride
Hydrogen bonds
Interfaces
Iron
Metals
Organic chemistry
Oxidation
Protonentransfer
Wasserstoffatomtransfer
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Summary: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. Kooperative Katalyse durch Fe und Cr resultiert in einer „Arbeitsteilung” bei der elektrokatalytischen H2‐Oxidation. Der Prozess läuft ab, obwohl mit keinem der beiden Metalle alleine die H2‐Heterolyse gelingt.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201807510