One-electron Ni(II)/(I) redox couple: potential role in hydrogen activation and production.

The three-coordinate Ni(I) complex Ni(Cl)(P(2)), where P(2) is the diphosphine (iPr)DPDBFphos, reacts with the acids HCl·(dioxane) and 2,6-lutidinium chloride to generate Ni(H)(Cl)(P(2)) and Ni(Cl)(2)(P(2)). Photolysis of the Ni(H)(X)(P(2)) (for X = Cl, Br) results in formation of H(2) and the Ni(I) halide. This reaction also proceeds in reverse when heated.