TRICHLORO-MU-3-[TRIS(DIPHENYLPHOSPHANYL)METHANE]-TRIGOLD(I) - AURIOPHILICITY IN A TRIANGLE OF GOLD ATOMS

Trichloro-mu(3)-[tris(diphenylphosphanyl)methane]-trigold(I) (1) has been prepared by treating the tripod ligand tris(diphenylphosphanyl)methane with three equivalents of chloro(dimethyl sulfide)gold(I) is dichloromethane. 1 is converted into the tribromo (2), triiodo (3), and trimethyl derivatives (4) by treatment of suspensions of 1 in acetone with hydrogen bromide, potassium iodide, and methyllithium, respectively. Polycrystalline 1 has been studied by Mossbauer spectroscopy. From dichloromethane at room temperature cubic crystals of 1 are obtained, whereas at -30-degrees-C a monoclinic dichloromethane solvate of 1 crystallizes. X-Ray structure analyses have been performed for both forms. They contain essentially the same trinuclear complex with only marginal differences in the molecular dimensions. The striking structural feature of the complex is the triangular all-cis arrangement of the three gold atoms with rather short Au...Au contacts of 3.201(1) (cubic) and 3.281(1)-3.420(1) angstrom (monoclinic). This conformation is at variance with the structures of the free ligand (all-trans) and other adducts of the type HC(PPh2X)3 (cis/cis/trans) and is probably due to specific metal-metal interactions.