(Phosphine)gold(I)-silyloxides and -silylthiolates

The gold siloxanes Me₃PAuOSiMe₃ (1) and Ph₃PAuOSiPh₃ (2) were prepared from the corresponding (phosphine)gold(I) chlorides and sodium silanolates in dichloromethane as colorless, stable, crystalline solids. The crystal structure of compound 1 (monoclinic, space group C2/c, Z= 8) has been determined by X-ray methods. The lattice contains centro-symmetrical dimers with short Au-Au contacts (3.376(2) Å). The Si-O-Au angle is 121.0(4)°; the coordination geometry at the gold atom is close to linear. The hexaphenyl compound 2 is assumed to be a monomer like the methylpentaphenyl analog MePh₂PAuOSiPh₃, owing to steric effects. The thiosiloxane (silylthiolate) Ph₃PAuSSiPh₃ (3) was obtained from Ph₃PAu(acac) and Ph₃SiSH in CH₂Cl₂. It crystallizes in the monoclinic space group P2₁/n with Z=4 molecules in the unit cell. The compound is a monomer in the crystal with a narrow angle at the sulfur atom (95.0(1)°) and a linear coordination geometry at the gold atom. Association is again prevented by steric effects.