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

An uncommon nickel dinitrogen adduct and its tendency toward CO2 binding are investigated using a ((PPP)-P-Me)Ni scaffold. ((PPP)-P-Me)Ni(N-2) (1) and {((PPP)-P-Me)Ni}(2)(mu-N-2) (2) were prepared and their treatment with CO2 revealed the formation of ((PPP)-P-Me)Ni(eta(2)-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 ((PPP)-P-Me)Ni{COOB(C6F5)(3)} (4) possessing a Ni-mu-CO2-kappa C-2, O-B moiety.