ChemInform Abstract: Synthesis and Reactivities of Novel η2-(C,O) Alkylphenylketene Complexes of Nickel. Coordination-Mode Switching Reaction of the Ketene Ligand.

Abstract

Abstract A series of bis(tertiary phosphine)(alkylphenylketene)nickel complexes, Ni[(C 6 H 5 (R)CCO)L 2 [R  CH 3 ( a ), C 2 H 5 ( b ); L  P(C 6 H 5 ) 3 ( 1 ), P(C 6 H 5 ) 2 ( p -CH 3 C 6 H 4 ) ( 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 η 2 -(C,O) to be a ketene structure close to the structure of oxanickelacyclopropane. Based on their chemical reactivities and fluxional behaviors in 1 H and 13 C NMR, the ketene moieties of 1 and 2 switch their coordination-mode from η 2 -(C,O) to η 2 -(C,C) type via an associative process involving binuclear μ-ketene intermediates prior to undergoing further reactions.