[Ni(OMe)]-mediated reductive activation of CO affording a Ni(κ-OCO) complex.

Carbon dioxide is expected to be employed as an inexpensive and potential feedstock of C sources for the mass production of valuable chemicals and fuel. Versatile chemical transformations of CO, insertion of CO producing bicarbonate/acetate/formate, cleavage of CO yielding μ-CO/μ-oxo transition-metal complexes, and electrocatalytic reduction of CO affording CO/HCOOH/CHOH/CH/CH/oxalate were well documented. Herein, we report a novel pathway for the reductive activation of CO by the [Ni(OMe)(P(CH-3-SiMe-2-S))] complex, yielding the [Ni(κ-OCO˙)(P(CH-3-SiMe-2-S))] complex. The formation of this unusual Ni(κ-OCO˙) complex was characterized by single-crystal X-ray diffraction, EPR, IR, SQUID, Ni/S K-edge X-ray absorption spectroscopy, and Ni valence-to-core X-ray emission spectroscopy. The inertness of the analogous complexes [Ni(SPh)], [Ni(CO)], and [Ni(NH)] toward CO, in contrast, demonstrates that the ionic [Ni(OMe)] core attracts the binding of weak σ-donor CO and triggers the subsequent reduction of CO by the nucleophilic [OMe] in the immediate vicinity. This metal-ligand cooperative activation of CO may open a novel pathway promoting the subsequent incorporation of CO in the buildup of functionalized products.