Gold-197 Mössbauer and 31P-{1H} nuclear magnetic resonance spectroscopic studies on gold(I) 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.