Synthesis and Study of Cationic, Two-Coordinate Triphenylphosphine- Gold-Complexes

Cationic, two-coordinate triphenylphosphine-gold(I)-complexes of the form [(PPh3)Au(ligand)]+ SbF6- (ligand=4-methylstyrene, 1SbF6), 2-methyl-2-butene (3SbF6), 3-hexyne (6SbF6), 1,3-cyclohexadiene (7SbF6), 3-methyl-1,2-butadiene (8SbF6), and 1,7-diphenyl-3,4-heptadiene (10SbF6) were generated in situ from reaction of [(PPh3)AuCl], AgSbF6, and ligand at -78 degrees C and were characterized by low-temperature, multinuclear NMR spectroscopy without isolation. The ligands of these complexes were both weakly bound and kinetically labile and underwent facile intermolecular exchange with free ligand (G approximate to 9kcalmol-1 in the case of 6SbF6) and competitive displacement by weak sigma donors, such as trifluoromethane sulfonate. Triphenylphosphine-gold(I)-complexes were thermally unstable and decomposed above -20 degrees C to form the bis(triphenylphosphine) gold cation [(PPh3)2Au]+SbF6- (2SbF6).