Synthesis and characterization of functionalized phosphenium ions, stabilized by two intramolecular dative P ← N bonds

Article abstract of DOI:10.1016/S0022-328X(96)06938-0

ArPH₂ (Ar = [C₆H₃(CH₂NMe₂)₂-2,6]) 3 undergoes hydride abstraction on treatment with trityl cation to give the stabilized phosphenium ion [ArPH]⁺BF^-₄ 4a. The same cation was prepared by reaction of 3 with BrCCl₃ (4b) and also by lithiation of 3 followed by treatment with I₂ (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, DIBAL-H reduction of [ArPX]⁺X^- gives [ArPH]⁺X^-. This last reaction constitutes a transformation of a stabilized and functionalized phosphenium ion into a different ion. Confirmation of the structure of these salts was given by single-crystal X-ray diffraction analysis of [ArPH]⁺PF^-₆ 4e.