C–F Activation and hydrodefluorination of fluorinated alkenes at rhodium

Abstract

Reaction of [RhH(PEt3)4] (9) with hexafluoropropene (1) affords the C–F activation product [Rh{(Z)-CFCF(CF3)}(PEt3)3] (4) as well as Et3P(F){(Z)-CFCF(CF3)} (11). In contrast, addition of (E)-1,2,3,3,3-pentafluoropropene (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)2F(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.