Competing reaction pathways of 3,3,3-trifluoropropene at rhodium hydrido, silyl and germyl complexes: C-F bond activation versus hydrogermylation

The reaction of the silyl complex [Rh{Si(OEt) }(PEt ) ] (1) with 3,3,3-trifluoropropene afforded the rhodium complex [Rh(CH CHCF ){Si(OEt) }(PEt ) ] (2) which features a bonded fluorinated olefin. In contrast the rhodium hydrido complex [Rh(H)(PEt ) ] (3) yielded on treatment with 3,3,3-trifluoropropene in the presence of a base the fluorido complex [Rh(F)(PEt ) ] (4) together with 1,1-difluoro-1-propene by C-F bond activation. At low temperature the intermediate fac-[Rh(H)(CH CHCF )(PEt ) ] (5) was detected by NMR spectroscopy. The germyl complex [Rh(GePh )(PEt ) ] (6) reacted also with 3,3,3-trifluoropropene by C-F bond activation affording again the fluorido complex [Rh(F)(PEt ) ] (4) as well as the (3,3-difluoroallyl)triphenylgermane 7. The catalytic hydrogermylation of 3,3,3-trifluoropropene in the presence of various germanium hydrides under mild conditions was developed by employing complex 6 as a catalyst. The molecular structures of both germane derivatives (3,3-difluoroallyl)triphenylgermane 7 and 1,1,1-trifluoropropane-3-triphenylgermane 8 were determined by X-ray crystallography.