Gold anionic compounds

The most convenient pathway to this important class of compounds is the reaction of alkynes RG=GH with salts of the bis(acetylacetonato)gold anion.71 This reaction leads to almost any type of target compounds, including those with R = H, alkyl, alkenyl, alkynyl, aryl, heteroaryl, etc. (Q = metal or quaternary or PPN cation Equation (22)). 

A series of dinuclear anionic gold or mixed gold(I)/gold(III) compounds have been reported recently, all of them containing C6F5 as aryl group, probably due to the stabilizing... 

The square planar anion [Au(SCN)4]" has been characterized by infrared 428, 639, 663) and electronic 663) spectral measurements. In addition to the normal routes to it, the anion is formed by an apparently two-stage reaction, in which the amine is also displaced, between [Au(Et4dien—H)X]+ (X = Cl, Br) and NCS" 780). The AuBr4 anion is reduced by NCS to an unspecified gold(I) compound 428). The anion [Au(CNS)2] has been identified in solution and the effect of temperature on its stability has been studied 245), but the parent compound has not been characterized structurally. 

Late transition metal complexes of polypyridines are rare a number includes cyclometalated gold(III) compounds. Rare earth metals tend to transform polypyridines into radical-anion or dianion forms, or even structurally modify them by activation. 

Gold is resistant to acids only aqua regia dissolves it when tetrachloro-aurate(III), [AuC ]", anions are formed. Gold dissolves slowly in potassium cyanide, when dicyanoaurate(I), [Au(CN)2] , anions are formed. From both the monovalent and trivalent forms gold can easily be reduced to the metal. Gold(I) compounds are less stable than those of gold(III). 

Chemical analysis showed that the gold compound that precipitates on Ti02 is close to Au(CO(NH2)2) [41]. This compound results from a reaction between gold anions and urea or products of its decomposition, and forms only when the mixture is heated and reaches pH 3. 

Anionic and neutral organometallic gold(III) compounds with one or two organic radicals, CeFs or (2,4,6-(CH3)3C6H2), can efficiently mediate alkyne hydration in neutral media in refluxing methanol with a catalytic activity similar to that reported for NaAuCla (Table 2) [115]. The addition of acidic co-catalysts improves the catalytic activity of this reaction. 

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