Pentaco-ordinate phosphoranes. Olefinic and heteroaromatic dibiphenylylenephosphoranes

Abstract

Isobutenyl-2-furyl-, 2-thienyl-, and 2-benzo[b]thienyl-dibiphenylylenephosphoranes have been prepared from the appropriate organolithium reagent and dibiphenylylenephosphonium iodide. Their ³¹P and ¹H n.m.r. spectra are reported and the geminal coupling constant involving a phosphorus(V) atom is discussed. The u.v. spectra are believed to show two secondary bands corresponding to apical and equatorial phosphorus(V)–aryl conjugation.