Organogold I Complexes Preparation and Characterization

The dimethylaurate(I) anion was more readily isolated (9) when the lithium ion was complexed with pentamethyldiethylenetriamine (PMDT) [Eq. (2)]. The greater thermal stability of these complexes compared with their phosphine analogs was explained in terms of less-ready ligand dissociation and complexation of the lithium ion, preventing its attack at the gold center. 

The reactions of Li[AuMe2] with methyl iodide and methyl tosylate have been investigated (14), but the relatively high reactivity toward the latter remains unexplained. 

The most common route to alkyl or aryl complexes of the type [AuRL] is by the treatment of a halide complex with an alkyl- or aryllithium reagent. The first reactions of this type were performed (15) in 1959 [Eq. (5)], and the methyl and phenyl compounds were found to have chemical and thermal stabilities intermediate between those of the previously known organopalladium and -platinum complexes. 

It was shown (17) that phosphine exchange occurred in [AuMe(PR3)l complexes, but species with a coordination number greater than two were not observed, even with bidentate phosphorus ligands. Although such species were not observed, an associative mechanism was thought to be operative (16, 18). With trimethylphosphite also, only the two-coordinate complex [AuMe P(OMe)3 l was detected in solution (19). 

Polyfiuorophenylgold(I) complexes have been prepared with mono- and bidentate phosphine ligands (29). With [AuRf(PCy3)] (R, = C6H3F2 or C6H2F3) an equilibrium was established [Eq. (10)] involving the anionic diarylaurates described previously (Section II,A), which depended on the nature of the aryl group. 

---