The synthesis and chemistry of fluorovinyl-containing phosphines and the single crystal X-ray structure of SPPr i2(CFCF2)

Abstract

The first perfluorovinyl alkyl-containing phosphines of the type PR₂(CFCF₂) (R = Et, ⁱPr, Cy) are reported. The reactivity of these air- and moisture-stable materials has been explored, both at the phosphorus centre and at the fluorovinyl moiety. When PR₂(CXCF₂) (X = F, Cl) is reacted with LiAlH₄ a mixture of PR₂(CXCFH) isomers and other defluorinated materials are produced, but the reaction with LiAlH(OBu^t)₃ affords the single products Z-PR₂(CFCFH) or E-PR₂(CClCFH), respectively, in high yields. Reaction of the fluorovinyl alkyl phosphines with hydrogen peroxide, elemental sulfur or selenium yields fluorovinyl-containing phosphine oxides, sulfides and selenides, respectively. The phosphine sulfide SPPrⁱ₂(CFCF₂) is the first perfluorovinyl phosphorus(V) compound to be characterised crystallographically and it exhibits an unusually short [1.9358(9) Å] PS bond. Reaction of fluorovinyl phosphines with XeF₂ results in compounds of the type F₂PR₂(CFCF₂), identified on the basis of multinuclear NMR studies. These compounds decompose in the presence of moisture to yield the respective phosphine oxides. Reaction of OPPh₂(CFCF₂) with Br₂ results in bromine addition across the double bond to give OPPh₂(CFBrCF₂Br).