Synthesis and reactivities of novel η2-(C,O) alkylphenylketene complexes of nickel. Coordination-mode switching reaction of the ketene ligand

Article abstract of DOI:10.1016/0022-328X(92)83233-8

A series of bis(tertiary phosphine)(alkylphenylketene)nickel complexes, Nia), C2H5 (b); L = P(C6H5)3 (1), P(C6H5)2(p-CH3C6H4) (2)>, were isolated from the reaction of bis(1,5-cyclooctadiene)nickel with alkylphenylketene in the presence of the corresponding tertiary phosphines.The spectroscopic analyses of 1 and 2 suggest η²-(C,O) to be a ketene structure close to the structure of oxanickelacyclopropane.Based on their chemical reactivities and fluxional behaviors in 1H and 13C NMR, the ketene moieties of 1 and 2 switch their coordination-mode from η²-(C,O) to η²-(C,C) type via an associative process involving binuclear μ-ketene intermediates prior to undergoing further reactions.