Synthesis of Arylbis[(triorganophosphine)gold(I)]oxoniuni Tetrafluoroborates [RO(AuPR′₃)₂]⁺BF₄⁻. Crystal Structure of (8-Quinolinyl)bis[(triphenylphosphine)gold(I)]oxonium Tetrafluoroborate

Potassium phenolate, PhO⁻K⁺, was reacted with 2 equiv of a (triorganophosphine)gold(I) tetrafluoroborate, [R₃PAu]⁺BF₄⁻, in THF to give novel oxonium salts of the type [PhO(AuPR₃)₂]⁺BF₄⁻ [R = Ph (2a), 2-MeC₆H₄ (2b), Et (2c)]. The compounds were obtained in good yields and have been characterized by NMR spectroscopy as well as mass spectrometry and elemental analysis. Treatment of potassium quinolin-8-olate with 2 equiv of (triphenylphosphine)gold(I) tetrafluoroborate also yields a dinuclear complex, [(C₉H₆N)O(AuPPh₃)₂]⁺BF₄⁻ (3). The cation of compound 3 appears to be fluxional in haloalkane solution at room temperature, with the quinolyl group interacting alternatingly with both gold atoms, but at low temperature the compound shows two inequivalent gold atoms. The unsymmetrical ground-state structure could be confirmed by a single-crystal X-ray diffraction study. Crystal data: 3·2C₄H₈O, triclinic P1̄ (No. 2), a = 12.721(1) Å, b = 14.381(1) Å, c = 14.730(1) Å, α = 92.69(1)°, β = 93.50(1)°, γ = 100.83(1)°, Z = 2, R (R_w) = 0.040 (0.045).