ω-Monofluoroalkylrhodoximes: synthesis and structures of [Rh{(CH2)nF}(dmgH)2(PPh3)] (n=1, 3) and CF activation reactions

[Rh(dmgH)2(PPh3)]− ([Rh]−), synthesized by reduction of [Rh]Cl with NaBH4 in methanolic KOH, reacts with 1,ω-dihaloalkanes X(CH2)nF (X=Cl, n=1; X=Br, n=3) forming [Rh]CH2F (2a) and [Rh](CH2)3F (2b). Reaction of [Rh]− with BrCH2CH2F affords instead of the expected 2-fluoroethyl complex the dinuclear complex [Rh]CH2CH2[Rh] (4) exhibiting an unexpected CF bond activation. Complexes 2a and 2b were fully characterized by NMR spectroscopy (1H, 13C, 31P, 19F) and by X-ray diffraction. Complex 2a crystallizes as a dimer with crystallographically imposed Ci symmetry. The monomeric entities are linked via two OH⋯O hydrogen bridges. Complex 2b is monomeric in solid state. In both complexes there is a nearly linear PRhC moiety. Structural and NMR trans influence of fluoromethyl and 3-fluoropropyl ligand is discussed.