Metallaphosphorane Chemistry: Preparations, Structures, and Reactivities

Abstract

Abstract Transition-metal phosphorane complexes, [Cp(CO)2M{P(OC6H4Y)2}] (M = Fe, Ru; Y = NH, NMe, O) have been prepared from [Cp(CO)2M{P(OPh)3}]PF6, o-HOC6H4YH, and a Lewis base. With the use of Et4NF in place of o-HOC6H4YH, [Cp(CO)2Fe(PF4)] and [Cp(CO)2Fe{P(OPh)F3}] have been prepared. These reactions involve nucleophilic attacks of an organic or an inorganic nucleophile at a trivalent phosphorus coordinated to a transition metal and substitution on the phosphorus. The reaction of phosphorane HP(OC6H4NH)2 with a Lewis base leads to NH proton abstraction to give the amide HP(OC6H4NH)(OC6H4N−) Subsequent treatment of the anion with EX (MeI, [Cp(CO)2FeCl]) has yielded P-substituted phosphorane EP(OC6H4NH)2 whereas that with E′X (SiMe3Cl, GeMe3Cl, SnMe3Cl, [Cp(CO)CoI2]) has yielded N-substituted phosphorane HP(OC6H4NH)(OC6H4NE′) X-ray structure analyses and spectroscopic data for these metallaphosphoranes reveal that the transition metal fragment serves as a strong π donor toward a phosphorane fragment. The activation parameters for Berry pseudorotation around the phosphorus in several metallaphosphoranes have been determined. The reactivity of metallaphosphoranes was also examined. The iron and ruthenium phosphoranes react with a Lewis base to give Li[{η5-C5H4P(OC6H4Y)2}(CO)2M] In this reaction, one of the protons on the Cp ring is abstracted by the Lewis base and then migration of the phosphorane fragment to the Cp ring takes place. This constitutes the first reported migration of a hypervalent element fragment.