Reactivity of the Phosphinidene-Bridged Complexes [Mo2Cp(μ-κ1:κ1,η5-PC5H4)(η6-1,3,5-C6H3tBu3)(CO)2] and [Mo2Cp2(μ-PH)(η6-1,3,5-C6H3tBu3)(CO)2] toward Alkynes: Multicomponent Reactions in the Presence of Ligands

Abstract

The cyclopentadienylidene-phosphinidene complex [Mo2Cp(μ-κ1:κ1,η5-PC5H4)(η6-HMes*)(CO)2] (1) (Cp = η5-C5H5; Mes* = 2,4,6-C6H2tBu3) reacted with RC≡CR′ in refluxing toluene solutions to give the corresponding phosphide derivatives [Mo2Cp{μ-κ1,η5:κ1,η1-(C5H4)PCR═CR′}(η6-HMes*)(CO)2] (R = R′ = CO2Me; R = H, R′ = CO2Me, p-tol), displaying a phosphametallacyclobutene ring. In contrast, the phosphinidene complex [Mo2Cp2(μ-PH)(η6-HMes*)(CO)2] (2) reacted with MeO2CC≡CCO2Me at room temperature to give first the monocarbonyl phosphide-acyl complex [Mo2Cp2{μ-κ1:κ1,η3-PHC(CO2Me)═C(CO2Me)C(O)}(η6-HMes*)(CO)], the latter evolving progressively to the isomeric dicarbonyl [Mo2Cp2(μ-κ1:κ1,η1-PHC(CO2Me)═C(CO2Me)}(η6-HMes*)(CO)2] (Mo–P ca. 2.57 A). When different ligands such as CO, PMe3, P(OMe)3, or CNXyl were added at room temperature to toluene solutions containing compound 1 and different alkynes, relatively fast multicomponent reactions took place to give with good yields the corresponding phosphide-acyl complexes [Mo...