Abstract:  An investigation of the ligand-centered electrocatalytic reduction of protons using [Re(DPPT)3]n (n=0, +1. +2; DPPT= 2-diphenylphosphinebenzenethiolate) (Re-1)  , has been conducted.  Re-1  assists in the proton reduction of weak acids, such as acetic acid, under homogeneous conditions in dichloromethane with a calculated overpotential of -369 mV. The overpotential is similar to values recently reported for proton reduction catalyzed by metal-dithiolenes.1,2  Given the similarities in electronic structure and reactivity between Re-1  and metal-dithiolenes we propose a ligand-centered pathway via protonation of the thiolate donors to yield [Re-1 . H 2 ] 2+ , which releases H2 upon reduction regenerating Re-1 . Heterogeneous proton reduction with aqueous KHP buffer and solid supported Re-1  deposited onto previously developed functionalized Au microelectrodes, occurs at an overpotential of -431 mV. No significant proton reduction is observed with the Au microelectrodes in the absence of Re-1 . The heterogeneous system significantly enhances the stability and utility of the electrocatalyst, with only modest increases in overpotential. Zarkadoulas, A.; Koutsouri, E.; Mitsopoulou, C.A. Coord. Chem. Rev., 2012 ,256, 2424-2434.McNamara, Han. Z; Yin, C.-J.; Brennessel, W.W.; Holland, P.L.; Eisenberg, R. PNAS, 2012 , 109, 15594-15599.

Homogeneous and heterogeneous hydrogen production via ligand-centered proton reduction

246th National Meeting (2013)

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