Synthesis and some reactions of the rhodacyclopentadiene complex [Rh(CO)2{C4(CO2Me)4Rh(CO)2PPh3)}]

Abstract

Electron-deficient alkynes, RO₂CC₂CO₂R (R = H or Me), cyclotrimerize on heating in the presence of [{Rh(CO)₂(PPh₃)₂}₂], but other alkynes RC₂R′(R = R′= H, Ph, Et, and CMe₂OH; R = Ph, R′= H) failed to react under similar conditions. From the reaction with MeO₂CC₂CO₂Me, have been isolated [Rh₂(CO)₂(PPh₃)₄(MeO₂CC₂CO₂Me)] and the title compound [Rh(CO)₂{[graphic omitted]h(CO)₂(PPh₃)}]. A possible mechanism for the cyclotrimerization reaction is discussed.