Aurophilicity at sulfur centers. Synthesis of the polyaurated species [S(AuPR3)n](n-2)+ (n=2-6)

Article abstract of DOI:10.1016/0020-1693(95)04759-X

The reaction of two equivalents of [AuCl(PR₃)] with Li₂S in ethanol leads to the dinuclear complexes [S(AuPR₃)₂] (PR₃=PPh₃, PPh₂Me, P(p-Tol)₃), which contain bridging sulfido ligands. These complexes can add AuPR₃⁺ fragments stepwise to form the cationic species [S(AuPR₃)₃]⁺, [S(AuPR₃)₄]²⁺, [S(AuPR₃)₅]³⁺ and [S(AuPR₃)₆]⁴⁺. The reaction of [S(AuPR₃)₂] with different AuPR′₃⁺ fragments affords the mixed complexes [S(AuPR₃)_n(AuPR′₃)_m] ^(n+m-2)+ (n+m=5 or 6). The crystal structures of the complexes [S(AuPPh₂Me)₃] (OTf) and [S(AuPPh₃)₄] (ClO₄)₂ have been established by X-ray diffraction. [S(AuPPh₂Me)₃] (OTf): triclinic, space group P1, a = 11.547(4), b = 12.750(5), c = 15.355(6) A, α=97.55(3), β= 104.02(2), γ= 102.41(3)°, Z=2, T= -130 °C. In the crystal the cations are paired across symmetry centers with short intermolecular S...Au and Au...Au contacts. [S(AuPPh₃)₄](ClO₄)₂: monoclinic, space group P2₁/n, a = 18.028(10), b = 29.23(2), c = 18.183(10) A, β = 116.23(5)°, Z=4, T= -100 °C. The structure of the cation is square pyramidal, with the sulfur in the apical position; intramolecular gold-gold interactions are observed.