Diethylaminodifluorophosphine, PF2NEt2, forms dimeric, halogen-bridged rhodium(I) complexes [RhX(PF2NEt2)2]2 (X = Cl or I) which react reversibly with an excess of the ligand to give non-ionic, five-coordinate complexes RhX(PF2NEt2)4. Dimethylaminodifluorophosphine, PF2NMe2, forms analogous complexes but, in contrast with diethylaminodifluorophosphine, the complex RhCL(PF2NMe2)4 decomposes thermally to give initially an isolable tris complex RhCl(PF2NMe2)4 which has no known counterpart in CO or PF3 chemistry. The tris-complex decomposes thermally to give [RhCl(PF2NMe2)2]2. Bis(dimethylamino)fluorophosphine, PF(NMe2)2 forms a tris complex, RhCl PF(NMe2)23, but a dimeric bis-ligand complex could not be isolated. In contrast with tertiary phosphines and phosphites, the fluorophosphines do not form ionic rhodium(I) species. Monomeric derivatives such as Rh(acac)(PF2NEt2)2, Rh(C5H5)(PF2NEt2)2, RhCl(PF2NEt2)(PPh3)2 and RhCl(PPh3)(PF2NEt2)2 have been prepared. The complexes [RhCl(CO)2]2 and [RhCl(PF2NEt2)2] undergo ligand redistribution on mixing, the product consisting mainly of [RhCl(CO)(PF2NEt2)]2. 19F n.m.r, data are reported and used inter alia to show that Rh(acac)(PF2NEt2)2, but not Rh(C5H5)(PF2NEt2)2, exchanges rapidly with free PF2NEt2, and that, in RhCl(PPh3)(PF2NEt2)2, the fluorophosphine ligands are mutually cis. Bands in the infrared arising from P-F vibrations are reported and discussed. The dialkylaminofluorophosphines appear to be poorer π-acceptors and/or better σ-donors than PF3, but are better π-acceptors than phosphites.