Coupling of Carbomethoxy and Vinylidene Ligand in Molybdenum Complexes

Treatment of [Cp(dppe)(CO)MoCC(Ph)CH2CHCH2]I (2) with MeONa caused nucleophilic attack to occur at the terminal CO ligand. This is followed by a coupling reaction of the resulting carbomethoxy group with Cα of the vinylidene ligand accompanied with coordination of the terminal olefin to afford Cp(dppe)MoC(COOMe)C(Ph)CH2CHCH2 (5). Similar coupling was observed when [Cp(dppe)(CO)MoCC(Ph)CH2Ph]I (3) was treated with MeONa, but the reaction afforded the neutral allylic complex Cp(dppe)Mo[CH(COOMe)C(Ph)CHPh] (6). The structures of complexes 5 and 6 have been determined by X-ray diffraction analysis.