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

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.