Gold-197 Mössbauer and³¹P-{¹H} nuclear magnetic resonance spectroscopic studies on gold(<scp>I</scp>) complexes with tertiary phosphines

Abstract

Further studies on solutions of [AuXL]+ L and [AuL2]BPh4+ L (X = Cl or I; L = tertiary phosphine) show that for L = PBun2Ph or PPri2Ph, no more than three ligands can be co-ordinated to the gold atom, while for L = PPrn2Ph, PEt2Ph, PMePh2, or PMe2Ph, four ligands can be co-ordinated. However, for L = PMe2Ph the tris(ligand) complex is not observed. There is some evidence for association of the halide with [AuL2]+ for L = PPrn2Ph. Gold-197 Mössbauer data are reported for a range of complexes of types [AuXL] and [AuL2]Y (X = Cl or I, Y = BPh4 or ClO4), which are consistent with values for related compounds. The former show the curious trend that the isomer shift and quadrupole splitting are lower for X = I than for X = Cl. The four-co-ordinate complexes [AuL4]BPh4(L = PMe2Ph or PMePh2) follow previous trends, and the quadrupole splitting of [AuCl(PPh3)3] is consistent with the known distorted tetrahedral structure.