10.1021/ja9043104.s001 Marco Zimmer-De Iuliis Marco Zimmer-De Iuliis Robert H. Morris Robert H. Morris Kinetic Hydrogen/Deuterium Effects in the Direct Hydrogenation of Ketones Catalyzed by a Well-Defined Ruthenium Diphosphine Diamine Complex American Chemical Society 2009 hydrogenation 2. KIE RuH H 2 acetophenone H 2 gas DFT catalyst ketone mechanism D 2 gas 2009-08-12 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Kinetic_Hydrogen_Deuterium_Effects_in_the_Direct_Hydrogenation_of_Ketones_Catalyzed_by_a_Well_Defined_Ruthenium_Diphosphine_Diamine_Complex/2836048 The <i>trans</i>-dihydride complex <i>trans</i>-RuH<sub>2</sub>(NH<sub>2</sub>CMe<sub>2</sub>CMe<sub>2</sub>NH<sub>2</sub>)((<i>R</i>)-binap) (<b>1</b>) is an active catalyst for the homogeneous hydrogenation of ketones in benzene under pressure of H<sub>2</sub> gas. The mechanism of the catalysis is proposed to occur through a rapid transfer of a hydride from the ruthenium and a proton from the amine on <b>1</b> to the carbonyl of the ketone to give the product alcohol and a hydrido-amido intermediate RuH(NHCMe<sub>2</sub>CMe<sub>2</sub>NH<sub>2</sub>)((<i>R</i>)-binap) (<b>2</b>). The dihydride is then regenerated by the turnover-limiting heterolytic splitting of dihydrogen by complex <b>2</b>. In this work the kinetic isotope effect (KIE) is measured to be 2.0 (±0.1) for the reduction of acetophenone to 1-phenylethanol catalyzed by <b>1</b> using 8.0 atm of H<sub>2</sub> versus D<sub>2</sub> gas. DFT calculations predict a KIE of 2.1 for the described mechanism using the simplified catalyst RuH(NHCH<sub>2</sub>CH<sub>2</sub>NH<sub>2</sub>)(PH<sub>3</sub>)<sub>2</sub> with H<sub>2</sub> or the catalyst RuD(NDCH<sub>2</sub>CH<sub>2</sub>ND<sub>2</sub>)(PH<sub>3</sub>)<sub>2</sub> with D<sub>2</sub>. This supports the observation that deuterium scrambles into the catalyst when a pressure of D<sub>2</sub> is used. We discuss the significance of these results relative to the KIE of 2 that was reported by Sandoval et al. (<i>J. Am. Chem. Soc.</i> <b>2003</b> <i>125</i>, 13490) for the hydrogenation/deuteriation of acetophenone catalyzed by <i>trans</i>-RuH(η<sup>1</sup>-BH<sub>4</sub>)((<i>S</i>)-tolbinap)((<i>S,S</i>)-dpen) in basic isopropanol/isopropanol-<i>d</i><sub>8</sub>.