Catalytic hydrogen evolution from a covalently linked dicobaloxime
Abstract
A dicobaloxime in which monomeric Co(III) units are linked by an octamethylene bis(glyoxime) catalyzes the reduction of protons from p-toluenesulfonic acid as evidenced by electrocatalytic waves at -0.4 V vs. the saturated calomel electrode (SCE) in acetonitrile solutions. Rates of hydrogen evolution were determined from catalytic current peak heights (k_(app) = 1100 ± 70 M^(-1) s^(-1)). Electrochemical experiments reveal no significant enhancement in the rate of H2 evolution from that of a monomeric analogue: The experimental rate law is first order in catalyst and acid consistent with previous findings for similar mononuclear cobaloximes. Our work suggests that H_2 evolution likely occurs by protonation of reductively generated Co^(II)H rather than homolysis of two Co^(III)H units.
Additional Information
© 2012 by the National Academy of Sciences. Edited by Thomas J. Meyer, University of North Carolina at Chapel Hill, Chapel Hill, NC, and approved June 14, 2012 (received for review February 7, 2012). Published online before print July 11, 2012. We thank Ian Stewart, Alex Miller, Bryan Stubbert, Charles McCrory, Xile Hu, and Jonas Peters for insightful discussions. This work was supported by the NSF Center for Chemical Innovation (Powering the Planet, CHE-0802907), the Arnold and Mabel Beckman Foundation, CCSER (Gordon and Betty Moore Foundation), and the BP MC2 program. CNV is grateful for support from the Caltech Summer Undergraduate Research Program and an Amgen Scholars Fellowship. JLD was supported by an NSF Graduate Research Fellowship. Author contributions: C.N.V., J.L.D., J.R.W., and H.B.G. designed research; C.N.V. and J.L.D. performed research; C.N.V. and J.L.D. contributed new reagents/analytic tools; C.N.V., J.L.D., and B.S.B. analyzed data; and C.N.V., J.L.D., J.R.W., and H.B.G. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.Attached Files
Published - PNAS-2012-Valdez-15589-93.pdf
Supplemental Material - pnas.1118329109_SI.pdf
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Additional details
- PMCID
- PMC3465440
- Eprint ID
- 33819
- Resolver ID
- CaltechAUTHORS:20120904-101007499
- CHE-0802907
- NSF
- Arnold and Mabel Beckman Foundation
- Gordon and Betty Moore Foundation
- BP MC2 program
- Caltech Summer Undergraduate Research Fellowship (SURF)
- Amgen
- NSF Graduate Research Fellowship
- Created
-
2012-09-04Created from EPrint's datestamp field
- Updated
-
2021-11-09Created from EPrint's last_modified field
- Caltech groups
- CCI Solar Fuels