Cyclopentadienyl Ruthenium–Nickel Catalysts for Biomimetic Hydrogen Evolution: Electrocatalytic Properties and Mechanistic DFT Studies |
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Authors: | Sigolène Canaguier Loredana Vaccaro Dr Vincent Artero Dr Rainer Ostermann Jacques Pécaut Dr Martin?J Field Dr Marc Fontecave Prof |
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Affiliation: | 1. Laboratoire de Chimie et Biologie des Métaux, Université Joseph Fourier, Grenoble (France), CNRS, UMR 5249 (France), CEA, DSV/iRTSV, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France), Fax: (+33)?438789124;2. Laboratoire de Dynamique moléculaire Institut de Biologie Structurale ” Jean‐Pierre Ebel ” UMR CNRS/UJF/CEA 5075, 41 rue Jules Horowitz, 38027 Grenoble cedex 1 (France), Fax: (+33)?438785122;3. Laboratoire de Reconnaissance Ionique et Chimie de Coordination, UMR UJF/CEA‐E3, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France);4. Collège de France, 11 place Marcellin‐Berthelot, 75005 Paris (France) |
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Abstract: | The new dinuclear nickel–ruthenium complexes Ni(xbsms)RuCp(L)]PF6] (H2xbsms=1,2‐bis(4‐mercapto‐3,3‐dimethyl‐2‐thiabutyl)benzene; Cp?=cyclopentadienyl; L=DMSO, CO, PPh3, and PCy3) are reported and are bioinspired mimics of NiFe hydrogenases. These compounds were characterized by X‐ray diffraction techniques and display novel structural motifs. Interestingly, Ni(xbsms)RuCpCO]PF6] is stereochemically nonrigid in solution and an isomerization mechanism was derived with the help of density functional theory (DFT) calculations. Because of an increased electron density on the metal centers Eur. J. Inorg. Chem. 2007 , 18 , 2613–2626] with respect to the previously described Ni(xbsms)Ru(CO)2Cl2] and Ni(xbsms)Ru(p‐cymene)Cl]+ complexes, Ni(xbsms)RuCp(dmso)]PF6] catalyzes hydrogen evolution from Et3NH+ in DMF with an overpotential reduced by 180 mV and thus represents the most efficient NiFe hydrogenase functional mimic. DFT calculations were carried out with several methods to investigate the catalytic cycle and, coupled with electrochemical measurements, allowed a mechanism to be proposed. A terminal or bridging hydride derivative was identified as the active intermediate, with the structure of the bridging form similar to that of the Ni? C active state of NiFe hydrogenases. |
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Keywords: | bioinspired chemistry catalysis hydrogenases nickel ruthenium |
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