Formation of a nickel carbon dioxide adduct and its transformation mediated by a Lewis acid

Abstract

An uncommon nickel dinitrogen adduct and its tendency toward CO₂ binding are investigated using a (PP^MeP)Ni scaffold. (PP^MeP)Ni(N₂) (1) and {(PP^MeP)Ni}₂(μ-N₂) (2) were prepared and their treatment with CO₂ revealed the formation of (PP^MeP)Ni(η²-CO₂) (3). This is a new type of CO₂ binding for a zero-valent nickel center supported by three donor ligands, reminiscent of the CODH active site environment. Clear unique structural differences in 3 are evident when compared with previous 4-coordinate Ni–CO₂ adducts. Compound 3 when treated with B(C₆F₅)₃ gives the Lewis acid–base adduct (PP^MeP)Ni{COOB(C₆F₅)₃} (4) possessing a Ni-μ-CO₂-κ²C,O-B moiety.