Synthesis of perfluorodiphenylphosphinic acid and its potassium and oxonium salts; crystal structure of oxonium perfluorodiphenylphosphinate

Article abstract of DOI:10.1016/S0022-1139(96)03562-2

The syntheses of perfluorodiphenylphosphinic acid, oxonium perfluorodiphenylphosphinate (perfluorodiphenylphosphinic acid monohydrate), and the potassium salt are described. Crystals of (C₆F₅)₂PO^-₂H₃O⁺ [(C₆F₅)₂PO(OH)·H₂O] are monoclinic, a = 33.541(2) A, b = 6.512(3) A, c = 30.238(2) A, Z = 16, space group C2/c. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = R_w = 0.037 for 3792 reflections with 1≥3σ(1), respectively. The crystal structure contains H₃O⁺ cations and (C₆F₅)₂PO^-₂ anions (two of each per asymmetric unit), linked by two strong, symmetrical hydrogen bonds (O...O≈2.4 A) and four more-normal hydrogen bonds (O...O≈2.6 A). P-C bonds are longer and P-O bonds shorter than in the perhydro analog.