Gold cyanide complexes

Alkene complexes Alkynyl complexes Ammine complexes Aqueous chemistry Arsine complexes Auranofin Auride ion Aurophilicity Binary compounds Bond lengths acetylacetonate complex alkyls and aryls ammine complexes carboxylates cyanide complexes dialkyl sulphide complexes dithiocarbamates to gold... 

The small amounts of gold contained in low-grade ores can be extracted using a combination of oxidation and complexation. Gold is oxidized to Au, which forms a very strong complex with cyanide anions Au ((2 q) + l CN(a q) [Au (CN)2] aq) K -lx 10 Suppose that a sample of ore containing 2.5 X 10 mol of gold is extracted with 1.0 L of 4.0 X 10 M aqueous KCN solution. Calculate the concentrations of the three species involved in the complexation equilibrium. 

Although 6 Is most prevalent, a coordination number of 4 Is also common, and several important complexes have a coordination number of 2. In addition, a few complexes display coordination numbers of 3, 5, and 7. Examples of coordination number 2 include the silver-ammonia complex and the gold-cyanide complex, both described in Chapter 18. To minimize ligand-ligand repulsions, a complex with a coordination number of 2 is invariably linear, as Figure 20-6 shows. 

Plaksin, I. N. Laskorin, B. N. Shivrin, G. N. Liquid extraction of complex gold and silver cyanides from cyanide solutions. Tsvetnye Metally 1961, 34, 20-23. 

Morphology of gold nanoparticles synthesised from gold chloride and gold cyanide complexes under evaporative conditions... 

No modification is observed in the dimensionality compared with that of the parent gold cyanide complex, but an increment in the thermal stability is described in the final compound. In the structure of [Cu(tmeda)][Au(CN)2]2 (tmeda = N,N,N, N -tetramethylenediamine) aurophilic interactions connect ID chains which contain copper(II)-bridging and pendant [Au(CN)2] units. In this case the aurophilic interactions increase the structural dimensionality from one to three. The compound is synthesized by reaction of Cu(C104)2.6H20, tmeda (tetramethylethylenediamine) and K[Au(CN)2]. The structure of Au2Cu(CN)4(tacn)] (tarn = 1,4,7- triazacyclono-nane) contains two different sort of chains. One of them contains gold atoms in an ABCDABCD- pattern (Figure 2.16a), and the other is built from two kinds of... 

An example of chemical destruction of an anionic species is the elution of aurocyanide from an anion-exchange resin with thiourea, a neutral ligand that reacts with gold cyanide in the presence of acid to form a cationic complex. The elution reaction can be described by the following equation ... 

Far less selectivity can be achieved in cyanide solution because many metals, both precious and base, form anionic complexes in even very dilute cyanide solution. This is illustrated by the equilibrium absorption isotherms for various metal ions in a leach liquor from a gold cyanidation plant on a strong-base resin (Figure 14).358... 

Senanayake, G. (2004b). Kinetics and reaction mechanism of gold cyanidation Surface reaction model via Au(I)-OH-CN complexes. Hydrometallurgy, 80, 1-12. 

Carbonyl Complexes of the Transition Metals Cluster Compounds Inorganometalhc Compounds Containing Transition Metal Main Group Elements Cyanide Complexes of the Transition Metals Dinuclear Organometallic Cluster Complexes Gold Inorganic Coordination Chemistry. 

The presence of carbonaceous material in the ore precipitates the gold in cyanide solutions, thus resulting in an increase of gold content in the cyanidation residue. For such complex gold-bearing ores, a roasting operation oxidizes the carbonaceous matter and thereby makes the ore more amenable to cyanidation. However, the alteration of the associated minerals presents new dissolution problems which must be solved. 

Ammonia complexes.. EflFect of complex formation on solubility. Cyanide complexes. The cyanide process of treating gold and silver ores. Complex halides and other complexes. Sodium thiosulfate as photographic fixer. Hydroxide complexes. Amphoteric hydroxides. Sulfide complexes. Equilibrium expressions for complex formation. Structural chemistry—tetrahedral, octahedral, square complexes. Existence of isomers. 

The recent literature describes several autocatalytic gold bath formulations which are not based on the gold cyanide complex and which are operated at a near-neutral or acidic pH. These baths have been reviewed recently by one of the present authors [168]. Among these new baths, those based on the thiosulfate gold complex are believed to deserve special attention. 

The reaction of cyanide with gold, in the presence of air and water, produces the gold-cyanide complex ion [63] ... 

---