Synthesis, Structure, and Hydroboration Reactivity of Anionic Nickel(0) Complexes Supported by Bidentate NHC-Pyridone Ligands

A family of anionic, formally nickel(0) complexes supported by bidentate NHC–pyridone ligands is described. The unsymmetric chelating environment and capping [K(18-crown-6)]+ countercation allow isolation of single-component, monometallic complexes in high yield. The steric and electronic properties are assessed through a battery of experimental (NMR, IR, UV–vis, X-ray diffraction) and computational tools. Catalytic activity for highly branched-selective hydroboration of styrene with HBpin is demonstrated. Control experiments implicate an important role of the pyridone in establishing reactivity and regioselectivity, suggesting the potential to leverage secondary coordination sphere effects with these single-component precatalysts for reagent activation and delivery.