Nature of interactions between phosphines and HO acids in aprotic solvents: nuclear magnetic resonance low-temperature studies

Abstract

Interactions between phosphines [PPh_nMe_3–n(3 n 1)] and pentachlorophenol, CF₃CO₂H and CH₃SO₃H in C₂H₅Cl–CDCl₃ solutions are examined by ¹H and ³¹P NMR experiments. The last two acids (AH) protonate the phosphines at –100 °C and the resulting cations are stabilized in (A—H)_n⋯A—H⋯A^–⋯H—PR⁺₃(n 0) hydrogen-bonded ion pairs and by homoconjugated ions: (A⋯H⋯A)^–(H—PR₃)⁺.