Phosphine and halide exchange between cyclopentadienylruthenium bis(triarylphosphine)halide complexes

Halide exchange between CpRu(PPh 3 ) 2 Br and either CH 3 C 5 H 4 Ru(PPh 3 ) 2 Cl, Cp*Ru(PPh 3 ) 2 Cl or cymeneRu(PPh 3 )Cl 2 most likely proceeds by phosphine dissociation as the initial step followed by a second, bimolecular step leading to exchange of chloride for bromide. Reactions between CpRu(PAr 3 ) 2 X and CpRu(PAr’ 3 )X' (Ar and Ar’ = Ph, p- FC 6 H 4 or p- MeOC 6 H 4 ; X, X' = Cl, Br, I) lead to both halide exchange and scrambling of the triarylphosphine ligands. Kinetic and equilibrium studies of phosphine exchange between CpRu(PAr 3 ) 2 X and PMePh 2 or PAr’ 3 suggest a dissociative interchange mechanism in toluene solution.