Gold complexes,

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. 

Cinellu, M.A. and Minghetti, G. (2002) Gold(l) and gold(lll) complexes with anionic oxygen donor ligands hydroxo, 0X0 and alkoxo complexes. Gold Bulletin, 35, 11. 

Shaw, C.F. Ill, Schaeffer, N.A., Elder, R.C., Eidsness, M.K., Trooster, J.M. and Calls, G.H.M. (1984) Bovine serum albumin-gold thiomalate complex gold-197 Moessbauer, EXAFS and XANES, electrophoresis, sulfur-35 radiotracer, and fluorescent probe competition studies. Journal of the American Chemical Society, 106, 3511-3521. 

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. 

Fig. 18. X-ray crystal structure of the injectable antiarthritic complex gold(I)-aurothiomalate 88 (side-chain on S omitted) showing the double helical chains. The right-handed helix shown contains thiomalate ligands with the R absolute configuration. Au-S bond lengths 2.283 and 2.286 A S-Au-S angles 178.88° and 169.41°. Adapted from (419).

Localization energies of some isomeric proton addition complexes (Gold and Tye 1952c) ... 

In addition to the synthetic advances, the study of the optical properties of these species is a growing field. Many complexes which exhibit these interactions are luminescent. Other interesting points are the induction of rotator phases or the modulation of magnetic properties by designing the appropriate heterometallic complexes. Gold-gold interactions are still a hot topic in gold chemistry. This is evidenced in the observation that some complexes which exhibit these interactions, characterized some years ago, are revisited and modified in order to study their properties. 

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. 

Hydrido complexes, gold-osmium, 27 209 iridium, 26 117, 27 19 iron, 26 244, 27 168 iron-tungsten, 26 336 manganese, 26 226 mercury-molybdenum-ruthenium,... 

Taylor, A. (2013). Developments in the processing of refractory complex gold ores. Presented at AusIMM Bendigo Technical Meeting, 2013, Melbourne, Australia. 

Gold(lll) Complexes. Gold(m) is isoelectronic with Pt(n), and its complexes therefore show many structural similarities to those of Pt(n). 

The formation of gold oligomers and, after a long time, of gold particles Au ,cn", that are also associated with complexed gold ions, is observed at 520 The... 

The trans influence of a ligand is the ability of a ligand to weaken the bond trans to itself in a complex. Gold(I) and gold(III) complexes are, in the simplest treatment, considered to use sp and dsp hybrid orbitals in forming linear and square planar complexes respectively. A good o donor, L, tends to concentrate gold 6s character in the AuL bond and the trans bond must then overlap with an orbital of low s character. A weaker and more ionic bond is then formed. 

The chemistry of gold is complex. Gold can exist in seven oxidation states -1,0, - -1, -1-2, +3, +4, and - -5. Apart fromAu in the colloidal and elemental forms, only Au+ and Au+ are known to form compounds that are stable in aqueous media and important in medical applications. The remaining oxidation states of -1, +2, +4, and +5 are not presently known to play a role in biochemical processes related to therapeutic uses of gold. Neither Au+ or Au+ forms a stable aquated ion ([Au(OH2)+ ] or [Au(OH2)4 ], respectively)... 

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