Gold complexes diamines

Uson, R., Laguna, A. and Villacampa, M.D. (1984) Mono and binuclear gold complexes with diamine and carbene ligands. Inorganica Chimica Acta, 81(1), 25-31. 

A major hurdle towards understanding the unusual low temperature CO oxidation activities of supported Au catalysis is that there is a wide variation in the reported CO oxidation activities over these catalysts [5]. This arises because these catalysts are very sensitive to the preparation procedures. Most supported Au catalysts are prepared with the chloride-containing chloroauric acid precursor, although there have been recent attempts to prepare these catalysts with precursors such as dimethyl gold acetonate [6], gold-phosphine complexes [7], and gold ethylene diamine complexes [8]. This discussion will focus on the complications that arise with chloride-containing precursors. 

Cyclic carbenes [46] are also described by the addition of a isocyanide to a diamine gold(III) complex (Scheme 3.2). 

A dinuclear gold-carbene complex is obtained when the reaction is carried out with the diamine HNCH3C6H12NHCH3 (Figure 7.13) [11]. This dinuclear compound... 

These ligands give simple linear gold(I) complexes, such as [Au(MeCN)2]+, [Au(NH3)2]+ and [AuCl(NH3)].307-310 In [AuCl(piperidine)], with r(AuN) = 207 pm, the molecules associate into tetramers through weak intermolecular Au Au interactions.96 Diamines can bridge between gold(I) centres, as in [aAuNH2CH2CH2NH2AuC6F5].311312... 

The NH protons of diamine and triamine complexes of gold(IH) are acidic, as shown by the data in Table 12. The acidity increases with the degree of substitution at nitrogen, and the trend is attributed primarily to steric effects.589-591... 

The gold-catalyzed oxidation of alcohols is a less-explored field. In one example, oxygen was used as the oxidant and the authors take advantage of the coordination of benzylic alcohols to an Au(l)-complex generated in situ from AuCl and a diamine anionic ligand. ... 

The attractive combination of transition metals and iodobenzene diacetate as strong oxidant allowed the subsequent development of additional diamination reactions. For example, in the presence of a conventional ttiphenylphosphino-gold(l)chloride complex, intramolecular diamination using ureas as nitrogen sources proceeds within a gold(l/lll) cycle with results that are comparable to the mentioned paUadium(II/IV) catalysis [99]. However, as the initial step consists of an anti-aminoauration, this reaction provides the opposite stereochemistry with respect to the overall product configuration. 

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