Bridging of trigoldsulfonium clusters by a silver(I) ion

Treatment of tris[(triphenylphosphine)gold(I)]-sulfonium tetrafluoroborate with AgBF₄ (molar ratio 2:1) in tetrahydrofuran affords a heptanuclear mixed-metal cluster trication {[(Ph₃P)₆Au₆AgS₂](tht)}³⁺ as the tetrafluoroborate salt. The crystal structure of the compound has been determined by X-ray diffraction. The silver atom is found in a bridging position between the two Au₃S units with short contacts to both sulfur atoms and to three out of six gold atoms. The coordination sphere of the silver atom is complemented by a tetrahydrofuran molecule. In di(tri)chloromethane solutions there is rapid site exchange of the silver coordination as shown by virtual equivalence of the phosphine ligands on the NMR time scale at ambient temperature.