C-F activation and hydrodefluorination of fluorinated alkenes at rhodium

Reaction of [RhH(PEt3)(4)] (9) with hexafluoropropene (1) affords the C-F activation product [Rh{(Z)-CF=CF(CF3)}(PEt3)(3)] (4) as well as Et3P(F){(Z)-CF=CF(CF3)} (11). In contrast, addition of (E)-1,2,3,3,3-penta.\fluoropropene (8) to 9 yields [Rh{(E)-C(CF3)=CHF}(PEt3)(3)] (12) together with [RhF(PEt3)(3)] (6) and (Z)-1,3,3,3-tetrafluoropropene (10). Treatment of 12 with hydrogen effects the formation of 1,1,1-trifluoropropane (2) and the fluoro compounds [RhF(PEt3)(3)] (6) and cis-mer-[Rh(H)(2)F(PEt3)(3)] (7). On treatment of 6 or of a mixture of 6 and 7 with HSiPh3 the complexes [RhH(PEt3)(3)] (3) and cis-fac-[Rh(H)(2)(SiPh3)(PEt3)(3)] (13) are obtained. Both compounds are capable of the C-F activation of hexafluoropropene (1) to afford 4. The molecular structure of complex 13 has been determined by X-ray crystallography.