A mechanistic study into the interconversion of rhodium alkyne, alkynyl hydride and vinylidene complexes

摘要

The conversion of the alkyne complex RhCl(PPr3i)(2)(eta(2)-PhC CH) into its vinylidene isomer RhCl(PPr3i)(2)(=C=CPhH) has been monitored via NMR spectroscopy in a range of solvents. In THF and hexane solution the reaction was observed to proceed via the alkynyl hydride complex Rh(H)Cl(PPr3i)(2)(-C=CPh). The kinetic profile of the reaction demonstrates that this species is an intermediate in the formation of the vinylidene complex.