High-Valent Nickel Complexes Supported by a Functionalized PC(sp3)P Pincer Ligand: Properties and Catalysis.

This article presents the synthesis and characterization of a series of robust high-valent organometallic nickel complexes stabilized by a functionalized PC(sp³)P pincer ligand. Notably, the nickel center, covalently confined within the three-dimensional ligand framework, exhibits predictable coordination and redox behavior, coupled with remarkable stability across oxidation states +2, +3, and +4. These states were found to interconvert via one-electron transfer reactions. Among these complexes, the Ni(III)-PC(sp³)P species was identified as an efficient catalyst for the mild and selective hydrosilylation of alkenes, operating through a non-oxidative mechanism that, in some cases, leads to the formation of vinyl silanes and polysilylated products. We demonstrated that, contrary to a widely accepted concept, high-valent metals can serve as viable candidates for hydrogenation catalysts.