Stable gold(I) complexes with chelate rings: solution studies of bis(phosphino)ethane complexes and X-ray crystal structure of bis[1,2-bis(diphenylphosphino)ethane]gold(I) hexafluoroantimonate–acetone (1/1)

Abstract

Bis-chelated four-co-ordinate gold(I)–phosphine complexes of 1,2-bis(diphenylphosphino)ethane (dppe) and 1,2-bis(diethylphosphino)ethane (depe) exhibit exceptionally high thermodynamic and kinetic stability both in the solid state and in solution at ambient temperatures. Their formation in solution has been studied by conductivity and 31P n.m.r. titrations. Complexes of [Au(depe)2]+ and [Au(dppe)2]+ have been prepared and characterized. These species exist in solution even at Au : bis(phosphine) ligand ratios of 1 : 0.75. The mixed species [Au(depe)(dppe)]+ exhibited a trans-gold 31P–31P n.m.r. coupling of 52 Hz. The title complex was crystallized and shown by X-ray crystallography to contain gold(I) with a flattened tetrahedral (closely D2d) co-ordination geometry (P–Au–P, 85–130°) chelated by two dppe ligands with Au–P bond lengths of 2.39–2.42 A. Crystals are monoclinic, space group P21/n. with a= 18.685(2), b= 19.414(2), c= 15.096(1)A, β= 91.69(1)°, and Z= 4; 4 811 reflections refined to R 0.062.