Gold complexes selenides

Figure 2.29 Examples of polynuclear gold complexes with selenide and diphosphine ligands.

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). 

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... 

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. 

Cyclohexyldienyl complexes, with Ti(IV), 4, 327 Cyclohexylisocyanides, with gold(I) halides, 2, 281 Cyclohexylphosphine, for semiconductor growth, 12, 9 Cyclohexyl selenides, preparation, 9, 480 Cyclohydrocarbonylation alkenes, 11, 515 alkynes, 11, 522 dienes, 11, 522 overview, 11, 511-555 for ring expansion, 11, 527 Cycloisomerizations, via silver catalysts, 9, 558 Cyclomanganation, product types, 5, 777-778 Cyclometallated azobenzenes, liquid crystals, 12, 251 Cyclometallated complexes for OLEDs... 

A dinuclear selenide complex anion [Au2(M-Se)2(Se4)2] is the product of the reaction" between [AuCN] and Na2 Ses. Square-planar gold(IIl) complexes are readily formed by a variety of bidentate sulfur-donor ligands such as toluene-1,2-dithiolate, maleonitriledithiolate, and dithiocarbamate. On oxidation with CI2 or Br2, [ Au(S2CNR)2 2] forms Au -Au complexes, which may be oxidized further to an Au complex. 

Lensch. C. Jones. P.G. Sheldrick. G.M. Crystal structures of the selenide- and sulfide-bridged gold(I) complexes [Se(AuPPh3)3]Pp6 and [S(AuPPh3)2-CH6Cl2. Z. Naturforch 1982. 37b. 944. 

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