Gold selenides

In the case of selenium compounds in the presence of water, only gold selenide, AuSe, is formed (309). 

The third is a gold selenide cube, [NaAui2Se8]3, reported by Kanatzidis et al. [34] The anion is made up of eight selenium atoms and 12 gold atoms. A sodium cation occupies the center of the complex. 

Metals less noble than copper, such as iron, nickel, and lead, dissolve from the anode. The lead precipitates as lead sulfate in the slimes. Other impurities such as arsenic, antimony, and bismuth remain partiy as insoluble compounds in the slimes and partiy as soluble complexes in the electrolyte. Precious metals, such as gold and silver, remain as metals in the anode slimes. The bulk of the slimes consist of particles of copper falling from the anode, and insoluble sulfides, selenides, or teUurides. These slimes are processed further for the recovery of the various constituents. Metals less noble than copper do not deposit but accumulate in solution. This requires periodic purification of the electrolyte to remove nickel sulfate, arsenic, and other impurities. 

Selenium occurs in the slimes as intermetallic compounds such as copper silver selenide [12040-91 -4], CuAgSe disilver selenide [1302-09-6], Ag2Se and Cu2 Se [20405-64-5], where x < 1. The primary purpose of slimes treatment is the recovery of the precious metals gold, silver, platinum, palladium, and rhodium. The recovery of selenium is a secondary concern. Because of the complexity and variabiUty of slimes composition throughout the world, a number of processes have been developed to recover both the precious metals and selenium. More recently, the emphasis has switched to the development of processes which result in early recovery of the higher value precious metals. Selenium and tellurium are released in the later stages. Processes in use at the primary copper refineries are described in detail elsewhere (25—44). 

Organ oselenium compounds, such as phosphine selenides, are being evaluated in solvent extraction systems for silver and gold (63). Also, potential pharmaceuticals containing selenium have been prepared (64). 

The mud or slime is coUected from the bottom of the electrolytic ceUs and pumped to the sUver refinery, where it is processed for recovery of copper, precious metals, selenium, and, in many cases, teUurium. The anode slime contains 2—20% selenium as copper and sUver selenides, whereas gold exists as the metal and in combination with teUurium. A flow diagram is shown in Figure 8. 

RAFT polymerization lends itself to the synthesis of polymers with thiol end groups. Several groups have utilized the property of thiols and dilhioesLers to bind heavy metals such as gold or cadmium in preparing brushes based on gold film or nanoparticles1 8 761 763 and cadmium selenide nanoparticles.763 76 1... 

Gold telluride iodide, AuTczI, was the first example of a gold chalco-genide halide, and was found in 1969 (305). Systematic investigations confirmed the existence of at least six compounds four telluride halides and two selenide halides (see Table IV). No sulfide halides have been reported. 

Gold(I) sulfide, AU2S gold(III) sulfide, AU2S3 gold(ni) selenide, Au2Se3. 

Zou S, Weaver MJ (1999) Surface-enhanced Raman spectroscopy of cadmium sulfide/cadmium selenide superlattices formed on gold by electrochemical atomic-layer epitaxy. Chem Phys Lett 312 101-107... 

Golan Y, Margulis L, Rubinstein I, Hodes G (1992) Epitaxial electrodeposition of cadmium selenide nanocrystals on gold. Langmuir 8 749-752... 

Phosphine sulfides or selenides are well-known ligands in gold(I) chemistry. With monophosphine complexes of the type [AuX(SPR3)] (X = C1, Br, CN PR3 = PPh3, PCy3, PPh2Py,... 

Gold(I) complexes with P,S (or Se) donor ligands are in many cases derived of phosphine sulfides or selenides as [Au2(PPh2CH2PPh2Se)2](C104)2,3140 and [Au(PPh2CH2PPh2Se)2]+ (595),1403,3141 [Au2(PPh3)2(p-SPPh2Py)](BF4)2,1427 or phosphine thioethers such as... 

A similar reaction occurs when alcohohc solutions of gold(lll) chloride and hydrogen selenide are mixed, producing gold(lll) selenide, Au2Se3, a black amorphous solid. 

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