Rhodium(I) Complexes with a η 1 -Fluorenyl- P -phosphanylphosphorane Ligand.

The first example of a P -phosphanylphosphorane, Flu═PCy 2 -PCy 2 ( L2 ; Flu = 9-fluorenyl), has been easily prepared by P-phosphination of lithiated 9-dicyclohexylphosphinofluorene (FluPCy 2 , L0 ) with chlorodicyclohexylphosphane. L2 constitutes a new type of P(III)-P(V) organophosphorus compound, a σ 3 λ 3 -σ 4 λ 5 species that is stable under an inert atmosphere in the solid state. The reaction of L2 with [Rh(diene) 2 ]BR 4 causes metalation of the benzylic carbon (C9) of fluorene, giving κ 2 -C,P complexes in which fluorene is coordinated in the η 1 form. A complex with the weakly coordinating BArF anion has been isolated and fully characterized, including its crystal structure obtained by X-ray diffraction.