The reactions of Fischer-type carbene complexes with ethene

Abstract The reactions of the anionic carbene complexes [(CO) n MCOPh] - (M = Fe, Cr, Mo, W) with ethene are described. The iron and chromium complexes yield predominantly propiophenone, formed by ethene insertion into the MCOPh moiety. For instance, [ cis -PPh 3 (CO) 4 CrCOPh][Li · 2Et 2 O] gave 63% yield of propiophenone. At 150°C, a double insertion of ethene, leading to CH 3 CH 2 CH(CH 3 )COPh, is observed. At this temperature products incorporating an odd number of carbon atoms, viz.: CH 3 CH 2 CH 2 COPh, CH 3 CH(CH 3 )COPh, CH 3 CH 2 CH 2 CH(CH 3 )COPh are also formed and have been isolated in up to 15% yield; a metathetic reaction path and ethene insertion are proposed to account for their formation.