Proton–hydride tautomerism in hydrogen evolution catalysis
Luis M. Aguirre Quintana, Samantha I. Johnson, Sydney L. Corona, Walther Villatoro, William A. Goddard III, Michael K. Takase, David G. VanderVelde, Jay R. Winkler, Harry B. Gray, James D. Blakemore
Abstract
Efficient generation of hydrogen from renewable resources requires development of catalysts that avoid deep wells and high barriers. Information about the energy landscape for H_2 production can be obtained by chemical characterization of catalytic intermediates, but few have been observed to date. We have isolated and characterized a key intermediate in 2e^– + 2H^+ → H_2 catalysis. This intermediate, obtained by treatment of Cp*Rh(bpy) (Cp*, η^5-pentamethylcyclopentadienyl; bpy, κ^2-2,2′-bipyridyl) with acid, is not a hydride species but rather, bears [η^4-Cp*H] as a ligand. Delivery of a second proton to this species leads to evolution of H_2 and reformation of η^5-Cp* bound to rhodium(III). With suitable choices of acids and bases, the Cp*Rh(bpy) complex catalyzes facile and reversible interconversion of H^+ and H_2.
Group Members
Quintana, L. M. A., Johnson, S. I., Corona, S. L., Villatoro, W., III, W. A. G., Takase, M. K., VanderVelde, D. G., Winkler, J. R., Gray, H. B., & Blakemore, J. D. (2016). Proton–hydride tautomerism in hydrogen evolution catalysis. *Proc. Natl. Acad. Sci. U.S.A.*, *113*(23), 6409-6414. https://doi.org/10.1073/pnas.1606018113