Early Transition-Metal Perfluoroalkyl Complexes

Elusive early transition-metal perfluoroalkyl complexes have been isolated and structurally characterized for the first time. Trifluoromethyltrimethylsilane, CF3SiMe3, serves as an excellent trifluoromethyl group-transfer reagent and reacts with the known Ti(IV) fluoride complex Cp2TiF2 to yield the novel Ti(IV) trifluoromethyl fluoride compound, Cp2Ti(CF3)(F) (1). Reaction of complex 1 with trimethylsilyltriflate (Me3SiOTf) affords the Ti(IV) trifluoromethyl triflate complex Cp2Ti(CF3)(OTf) (2). Both titanium perfluoroalkyl compounds have been characterized spectroscopically and by single-crystal X-ray analysis. The Ti-CF3 linkage in these complexes is remarkably robust and shows no evidence of an alpha-fluoride interaction (Ti...F-CF2) between the electrophilic Ti(IV) metal center and any of the C-F bonds in the trifluoromethyl group in the solid state or in solution.