Organometallic Nickel Complexes Supported by Pyridinophane Ligands and Their Oxidative Reactivity

The pyridinophane ligands RN3CX (X = H, Br) are well-established scaffolds that facilitat and stabilize nickel oxidative addition complexes to the proximal C(aryl)–X bond. In this study, we report the synthesis, detailed characterization, and reactivity of a series of Ni(II) and Ni(III) complexes supported by the MeN3CX ligand. Our findings demonstrate that Ni(II) complexes can be oxidized both chemically and aerobically to yield well-defined Ni(III) species. Excitingly, the Ni-disolvento complexes exhibit catalytic trifluoroethoxylation to generate the C–O coupled product. In addition, the Ni(III)-halide complex undergoes transmetallation with a Grignard reagent and subsequent C–C reductive elimination, while the β-hydride elimination side reaction is suppressed, outperforming its Ni(II) analogue.