Complexes of the platinum metals. Part V. Perfluorocarboxylato-derivatives

Perfluorocarboxylic acids, RFCO2H (RF= CF3, C2F5, or C6F5), react with hydrido(triphenylphoshine) or low-oxidation-state triphenylphosphine complexes of the platinum-group metals to yield a wide range of perfluorocarboxylato-derivatives. Products which have been prepared in this manner include [RuCl(OCOCF3)(CO)(PPh3)2], [Ru(OCORF)2(CO)(PPh3)2], [Ru(OCORF)2(CO)2(PPh3)2], [RuH(OCOCF3)(PPh3)3], [OsCl(OCORF)(CO)(PPh3)3], [OsH(OCORF)(CO)(PPh3)3], [Os(OCORF)2(CO)(PPh3)2], [OsH(OCORF)(CO)2(PPh3)2], [Os(OCORF)2(CO)2(PPh3)2], [OsH(OCOCF3)(PPh3)3], [Rh(OCORF)(PPh3)3], [Rh(OCORF)(CO)(PPh3)2], [IrH(OCORF)2(CO)(PPh3)2], and [Ir(H)2(OCORF)(PPh3)3]. The new complexes have been characterised and, where possible, their stereochemistry has been determined by i.r. and n.m.r. spectroscopy. The occurrence of a rapid intramolecular exchange between uni- and bi-dentate perfluorocarboxylate ligands in the complexes [M(OCORF)2(CO)(PPh3)2](M = Ru or Os) has been established by observation of temperature-dependent 19F n.m.r. spectra for the trifluoroacetate derivatives. Mechanisms involving oxidative addition of perfluorocarboxylic acids to the precursors, and subsequent reductive elimination of dihydrogen, are proposed for the reactions discussed. The tendency for unidentate perfluorocarboxylate ligands situated trans to strong σ-donor ligands to undergo alcoholysis is reported.