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Mechanism of H_2 Evolution from a Photogenerated Hydridocobaloxime

Dempsey, Jillian L. and Winkler, Jay R. and Gray, Harry B. (2010) Mechanism of H_2 Evolution from a Photogenerated Hydridocobaloxime. Journal of the American Chemical Society, 132 (47). pp. 16774-1677. ISSN 0002-7863. http://resolver.caltech.edu/CaltechAUTHORS:20110110-150437628

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Abstract

Proton transfer from the triplet excited state of brominated naphthol to a difluoroboryl bridged Co^I-diglyoxime complex, forming Co^(III)H, was monitored via transient absorption. The second-order rate constant for Co^(III)H formation is in the range (3.5−4.7) × 10^9 M^(−1) s^(−1), with proton transfer coupled to excited-state deactivation of the photoacid. Co^(III)H is subsequently reduced by excess Co^I-diglyoxime in solution to produce Co^(II)H (k_(red) = 9.2 × 10^6 M^(−1) s^(−1)), which is then protonated to yield Co^(II)-diglyoxime and H_2.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ja109351h DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ja109351hPublisherArticle
ORCID:
AuthorORCID
Winkler, Jay R.0000-0002-4453-9716
Additional Information:© 2010 American Chemical Society. Received October 17, 2010. Publication Date (Web): November 10, 2010. We thank Bruce Brunschwig, Alec Durrell, Maraia Ener, Jonas Peters, and Jeff Warren for helpful discussions and experimental advice. Charles McCrory and Jacob Good are acknowledged for generous assistance with GC measurements. This work was supported by an NSF Center for Chemical Innovation (Powering the Planet, CHE-0947829), the Arnold and Mabel Beckman Foundation, and CCSER (Gordon and Betty Moore Foundation). J.L.D. was supported by an NSF Graduate Research Fellowship.
Group:CCI Solar Fuels
Funders:
Funding AgencyGrant Number
NSFCHE-0947829
Arnold and Mabel Beckman FoundationUNSPECIFIED
Caltech Center for Sustainable Energy ResearchUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Record Number:CaltechAUTHORS:20110110-150437628
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20110110-150437628
Official Citation:Mechanism of H2 Evolution from a Photogenerated Hydridocobaloxime Jillian L. Dempsey, Jay R. Winkler, Harry B. Gray Journal of the American Chemical Society 2010 132 (47), 16774-16776
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21675
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:26 Jan 2011 22:14
Last Modified:16 Sep 2017 02:36

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