Gold(I) complexes of ketiminophosphanes and -phosphane sulfides

The reactions of chloro(dimethyl sulfide)gold(I) with equivalent quantities of the ketiminophosphane diphenyl(diphenylmethyleneamino)phosphane (1a) or its sulfide (1aS) lead to high yields of stable, crystalline 1:1 complexes with AuCl units attached to the phosphorus and sulfur atom, respectively. Tris(diphenylmethylene amino)phosphane (1c) gives the related complex (Ph2C=N)(3)PAuCl with the gold atom also selectively P-bound. Bis(diphenylmethyleneamino)phenyl phosphane (1b) could not be used because of its limited stability. Single-crystal X-ray diffraction studies have shown that there is no auxiliary coordination of the metal center by the imino functions of the ligands. The geometry of the P/S-Au-Cl moieties deviates only very slightly from Linearity. The angle at the sulfur atom in (Ph2C=N)Ph2PSAuCl is very small [94.30(3)degrees], but despite of the resulting rather open coordination there are no discernible intra-or intermolecular contacts in the lattice. Such contacts are also absent with (Ph2C=N)Ph2PAuCl and (Ph2C=N)(3)PAuCl owing to the bulk of the ligands. The 1:1 complexes do not react with an excess of (Me2S)AuCl. This finding, and the molecular structures of the 1:1 complexes, show very consistently that both phosphane and sulfide donors are far superior as ligands for gold(I) as compared to ketimine donor molecules.