Synthesis and co-ordination chemistry of perfluorovinyl phosphine derivatives. Single crystal structures of PPh(CFCF2)2, cis-[PtCl2{PPh2(CFCF2)}2] and [{AuCl[PPh2(CFCF2)]}2]

Abstract

Reaction of perfluorovinyllithium, derived from CF₃CH₂F, with chloro-substituted phosphines generated perfluorovinylphosphines of the type PPh_m(CFCF₂)_n and P(CFCF₂)_nCl_m (n + m = 3) in high yields. A low-temperature crystal structure determination of the air- and moisture-stable compound PPh(CF=CF₂)₂ provided the first reported structural data for any perfluorovinyl-containing material. There is considerable variation in the C–F bond distances [1.310(4), 1.321(4), 1.353(3) Å] within the perfluorovinyl group in the phosphine. The co-ordination chemistry of these ligands has been investigated via the synthesis of examples of late transition-metal complexes. The results of single crystal structural determinations of cis-[PtCl₂{PPh₂(CFCF₂)}₂] and [{AuCl[PPh₂(CFCF₂)]}₂]·0.5CH₂Cl₂ are reported. In both of these molecules short metal–phosphorus distances [d(Pt–P)_av = 2.231(3) and d(Au–P)_av = 2.217(2) Å] are observed compared with typical distances for similar phosphine complexes. A comparison of the electronic properties of these ligands with those of other phosphines, halogenophosphines and phosphites was made on the basis of a spectroscopic investigation of the carbonyl stretching frequencies of the complexes [Mo(CO)₅{PPh_m(CFCF₂)_n}] (n + m = 3).