Gold halides

Only AuF of the gold(I) halides is unknown in the solid state its stability can be examined by means of a Bom-Haber cycle, assuming that it would have an ionic lattice like AgF. (AuF has been generated in the gas phase from Au and CH3COF [22].) 

Its instability relative to its constituent elements is the result of the high value of 7] of gold and to its large enthalpy of atomization, which are not compensated for by the small lattice energy. 

AuBr and Aul are all prepared by cautious heating of Au2Xg (X = Cl, Br) or, in the case of Aul, direct synthesis 

Other methods are available, especially for AuCl, such as the decomposition of Au(CO)Cl. AuCl tends to disproportionate slowly at room temperature as predicted from the data in Table 4.5. 

Gold(III) iodide has not been definitely characterized in the solid state substances with this formula in the solid state are probably gold(I) polyiodides Au IJ AUI3 has also been detected in the gas phase (mass spectra). 

The photochemical reactivity of the iridium(III) complex IrCli is wavelength dependent. When an aqueous solution of IrCli is irradiated into the charge transfer band at 254 nm, the products are those resulting from both aquation IrCl5(H20) and reduction IrCl5(H20)  

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Carbene complexes have also been prepared by transmetallation reactions. Lithiated azoles react with gold chloride compounds and after protonation or alkylation the corresponding dihydro-azol-ylidene compounds, e.g., (381) or (382), are obtained.22 9-2264 Silver salts of benz-imidazol have also been used to obtain carbene derivatives.2265 Mononuclear gold(I) carbene complexes also form when trimeric gold(I) imidazolyl reacts with ethyl chlorocarbonate or ethyl idodate.2266,2267 The treatment of gold halide complexes with 2-lithiated pyridine followed by protonation or alkylation also yields carbene complexes such as (383).2268 Some of these carbene complexes show luminescent properties.2269-2271... 

The 1 1 complexes of alkynylgold compounds (L)AuC=CR with strong donors L can also be conveniently prepared from the corresponding gold halides (L)AuX (X = C1, Br, I), an alkyne HC=CR, and a base. For many representative examples, the reactions with an alkali alkanolate in an alcohol58 or with triethylamine in dichloro-methane are the methods of choice (Equation (13)).59... 

Gold halide tellurides have been prepared by this method for the first time. The conditions for the preparation of these compounds are listed in Table III. 

Cycloaurated gold halide complexes are also precursors to metallacyclic compounds with three gold-carbon bonds. The first examples of this type were the... 

This kind of comparison has been made only for the diastereoselective version of this reaction.13 Water was still used as solvent for the conversion of phenylacetylene, 2-benzyloxyheptanal, and piperidine (Scheme 12.3), but the reaction temperature was lowered to 60°C, room temperature, or even 0°C. As shown in Table 12.1, neither with copper halides (entry 1) nor with silver halides (entry 2) could any satisfactory results be obtained. Only gold halides were still reactive enough at these temperatures. With AuCl at 60°C, the diastereomeric ratio (dr) was still low (entry 3) lowering the temperature to room temperature led to a slight increase of the dr (entry 4) and going to 0°C further increased the dr, but at the same time diminished the yield. With Aul at room temperature (entry 5) and 0°C (entry 6), only marginally better results were obtained. 

Dialkylmercury compounds caimot be used for alkylating gold halides (as already noted by Frankland in 1864), while... 

Tetragoldmethane complexes are obtained from tetra-(boryl)methane compounds upon reaction with gold-halide complexes in the presence of an ionic fluoride (equation 35)." Tetragoldmethane species, such as (1), can only be isolated with bulky tertiary phosphines, L, which shield the molecule from further attack by [TAu]+ nucleophiles. With smaller ligands T, penta- and hexaauration occurs, leading to hypercoordinate carbon compounds. " " " ... 

The reaction of organolithiums or organomagnesium halide reagents with gold halides proceeds similarly to the copper halides in a 1 1 ratio. Their phosphine complexes can be isolated and characterized. In a 2 1 ratio, the transmetallation reaction is followed by ate complexation to form organoaurate complexes ... 

The gold halides provide examples of ail interesting plienomenon —the deep intense color often observed for a substance xohich contains... 

Adducts with Aluminum Trichloride, Antimony Pentachloride, and Gold Halides... 

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