Lewis Acid‐Tethered (cAAC)—Copper Complexes: Reactivity for Hydride Transfer and Catalytic CO 2 Hydrogenation

Abstract We present a series of borane‐tethered cyclic (alkyl)(amino)carbene (cAAC)‐copper complexes, including a borane‐capped Cu(I) hydride. This hydride is unusually hydridic and reacts rapidly with both CO 2 and 2,6‐dimethylphenol at room temperature. Its reactivity is distinct from variants without a tethered borane, and the underlying principles governing the enhanced hydricity were evaluated experimentally and theoretically. These stoichiometric results were extended to catalytic CO 2 hydrogenation, and the borane‐tethered (intramolecular) system exhibits ~3‐fold enhancement relative to an intermolecular system.