SYNTHESIS AND CHARACTERIZATION OF FUNCTIONALIZED PHOSPHENIUM IONS, STABILIZED BY 2 INTRAMOLECULAR DATIVE P[-N BONDS

ArPH2 (Ar=[C6H3(CH2NMe2)(2)-2,6]) 3 undergoes hydride abstraction on t reatment with trityl cation to give the stabilized phosphenium ion [Ar PH]+BF4- 4a. The same cation was prepared by reaction of 3 with BrCCl3 (4b) and also by lithiation of 3 followed by treatment with I-2 (4c). ArLi reacts with PX3 (X=Cl or Br) to give the stabilized phosphenium ion [ArPX]X-+(-) which affords 3 by LiAlH4 reduction. In contrast, DIB AL-H reduction of [ArPX]X-+(-) gives [ArPH]X-+(-). This last reaction constitutes a transformation of a stabilized and functionalized phosph enium ion into a different ion. Confirmation of the structure of these salts was given by single-crystal X-ray diffraction analysis of [ArPH ]+PF6- 4e. (C) 1997 Elsevier Science S.A.