摘要:
                                The phosphenium complexes Cp(OC)(2)M=P(t-Bu)(2) (M=Mo, W) (1a,b) react with diazoethylacetate (2) to yield the five-membered phosphametallacycles Cp(OC)(2)M-P(t-Bu)(2)-N(H)-N=C(CO2Et) (4a,b). From Cp(OC)(2)W=P(Ph)(Mes) (5) and 2 the nitrogen-free three-membered phosphametallacycle Cp(OC)(2)W-P(Ph)(Mes)-C(H)CO2Et (6) is obtained. The structures of 4b and 6 were determined by X-ray analysis.