Adducts of Mn and Re vinylidenes with P–OR nucleophiles: Hydrolysis rather than the intramolecular Michaelis–Arbuzov rearrangement

The reactions of vinylidene complexes Ср(CO)2Mn = C=C(H)Ph (Mn1) and Cp(CO)2Re = C=C(H)Ph (Re1) with P–OR nucleophiles P(OR)R'R" (OR = R' = R" = OMe, OEt, OPri, OPh; OR = OEt, R' = R" = Ph; OR = R' = OEt, R" = Ph) proceed as nucleophilic addition to the Cα vinylidene atom to initially afford zwitter-ionic complexes Z-Ср(CO)2M¯−C[+P(OR)R'R"] = C(H)Ph which were identified by spectroscopic methods and, in some cases, their molecular structures were confirmed by X-ray diffraction. These adducts are extremely sensitive to water and hydrolyzed by water traces to afford the corresponding η2-phosphorylalkene complexes Cp(CO)2M{η2-E-HC[P(O)R'R"] = C(H)Ph}. The isotopic label experiments with D2O and H218O showed the hydrolysis to proceed with the phosphorus–oxygen bond cleavage and binding of the water hydrogen to the carbon atom bearing the > P=O group.