Difluorophosphines, RPF2, containing the electronegative substituents, R = CF, and CsH5, will undergo redox disproportionation with formation of tetrafluorophosphoranes and cyclopolyphosphines, in accord with the overall equation 10 RPF2 --+a-5 RPF4 + (RP),, (n = 4, 5 for R = CF,: n = 5 for R = C6H5). The identity of the products, all previously known, was established by comparison of their physical properties (n.m.r. and mass spectra, i.r. spectra, X-ray powder diagram, etc.) to those of the authentic compounds.IT has been amply demonstrated that the products of the reaction of chlorophosphines, R,PC1 -n with Group V trifluorides (AsF,, SbF,) are the fluorophosphoranes, R,PFS_~, rather than the expected fluorophosphines, R,PF,-,.2-5The latter were obtained, however, in the case of chlorophosphines containing electronegative substituents such as perhalogenoalkyl or perhalogenoaryl groups where no redox reaction took place.6-10It was noted in 1959 l1 and confirmed in 1965 l2 that an alkyldifluorophosphine such as MePF,, on standing at room temperature or, more rapidly, on being heated, will undergo a peculiar redox disproportionation, expressed by the following overall equation :