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A Bimetallic Nickel–Gallium Complex Catalyzes CO2 Hydrogenation via the Intermediacy of an Anionic d10 Nickel Hydride

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posted on 12.09.2017, 00:00 by Ryan C. Cammarota, Matthew V. Vollmer, Jing Xie, Jingyun Ye, John C. Linehan, Samantha A. Burgess, Aaron M. Appel, Laura Gagliardi, Connie C. Lu
Large-scale CO2 hydrogenation could offer a renewable stream of industrially important C1 chemicals while reducing CO2 emissions. Critical to this opportunity is the requirement for inexpensive catalysts based on earth-abundant metals instead of precious metals. We report a nickel–gallium complex featuring a Ni(0)→Ga­(III) bond that shows remarkable catalytic activity for hydrogenating CO2 to formate at ambient temperature (3150 turnovers, turnover frequency = 9700 h–1), compared with prior homogeneous Ni-centered catalysts. The Lewis acidic Ga­(III) ion plays a pivotal role in stabilizing catalytic intermediates, including a rare anionic d10 Ni hydride. Structural and in situ characterization of this reactive intermediate support a terminal Ni–H moiety, for which the thermodynamic hydride donor strength rivals those of precious metal hydrides. Collectively, our experimental and computational results demonstrate that modulating a transition metal center via a direct interaction with a Lewis acidic support can be a powerful strategy for promoting new reactivity paradigms in base-metal catalysis.