Copper and Gold

11 Copper and Gold. - Structures of trinuclear [CU3(s-02CPh)2(s mesltyl)] with a 3-centre, 2-electron Cu-C-Cu interaction,298 and of tetranuclear [Cu4(M3-CsCPh)4(PPh3)4]299 are reported. 

The role played by the ground- and excited-state potential surfaces in the temperature dependence of the electronic spectrum of the planar [CuCl J ion has been investigated.  

A study of the photoredox reactions of some gold porphyrins has shown that chlorogold meso-tetralcis(4-W-methvlDvr idyl) -porphine tetrachloride is a durable catalyst for electron transfer processes Involving water. 

The distorted octahedral cluster [Cug(M3-oxl)4 /t-Br)2l (oxl - 4,4-dimethyl-2-oxazoline-4-methylphenyl) has four two-electron three-centre bonded aryl bridges.Clusters [Au8(PPh3)7(CNR) ]2+. [Au9(PPh3)g(CNR)2] + and 

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In the Commonwealth of Independent States (CIS, formerly the USSR), nearly 50% of the CIS production comes from Ka2akhstan. Silver is produced from the lead—2inc mines at Ostkamen, Shymkent, and Leninogorsk (ca 1000 t) and also in Russia s Far East, where it is a by-product of the tin deposits near Khabarovsk, and of the copper and gold deposits in the Ural Mountains. 

The Group 1 elements are soft, low-melting metals which crystallize with bee lattices. All are silvery-white except caesium which is golden yellow "- in fact, caesium is one of only three metallic elements which are intensely coloured, the other two being copper and gold (see also pp. 112, 1177, 1232). Lithium is harder than sodium but softer than lead. Atomic properties are summarized in Table 4.1 and general physical properties are in Table 4.2. Further physical properties of the alkali metals, together with a review of the chemical properties and industrial applications of the metals in the molten state are in ref. 11. 

AgPh is a colourless solid [144] that is rather insoluble in non-donor solvents and appears to be polymeric (AgPh) (n > 10) in addition mixed compounds (AgPh) .AgN03 (n = 2,5) can also be obtained that involve silver clusters. Mesitylsilver is a thermally stable (but light-sensitive) white crystalline solid in the solid state it is tetrameric (in contrast to the pentameric copper and gold analogues) ... 

Copper and gold carborane complexes are discussed with the metalloboranes ( 6.5.3.4.). 

There are scattered reports on isocyanide complexes of other metals including copper and gold, vanadium, and several lanthanides and actinides. 

Konopka, M., Rousseau, R., Stich, I. and Marx, D. (2004) Detaching Thiolates from Copper and Gold Clusters Which Bonds to Break Journal ofthe American Chemical Society, 126, 12103-12111. 

Eberhardt, W., Cantor, R., Greuter, F. and Plummer, E.W. (1982) Photoemission from condensed layers of molecular hydrogen on copper and gold. Solid State Communications, 42, 799-802. 

Even when complete miscibility is possible in the solid state, ordered structures will be favored at suitable compositions if the atoms have different sizes. For example copper atoms are smaller than gold atoms (radii 127.8 and 144.2 pm) copper and gold form mixed crystals of any composition, but ordered alloys are formed with the compositions AuCu and AuCu3 (Fig. 15.1). The degree of order is temperature dependent with increasing temperatures the order decreases continuously. Therefore, there is no phase transition with a well-defined transition temperature. This can be seen in the temperature dependence of the specific heat (Fig. 15.2). Because of the form of the curve, this kind of order-disorder transformation is also called a A type transformation it is observed in many solid-state transformations. 

The carbon monoxide prevents reoxidation of the hot copper. A further temperature rise to about 900°C results in the copper and gold (or silver) at the surface of the parts interacting to form a eutectic. The eutectic melts and runs freely, wetting the surface as well as the attached wires or granules. When the assemblage is finally cooled, the eutectic solidifies, firmly joining the wires or granules to the now decorated surface. 

The Na-Ca and K-Fe-(Ca) alteration assemblage hosting iron-oxide, copper and gold mineralization and spatial and temporal relationship between mineralization and alteration, as well as the oxide and sulfide mineralogy at amli (Balikesir) suggest that it has characteristics more akin to Fe-oxide-Cu-Au systems. 

During beneficiation of clay-containing copper-gold ores, the use of small quantities of Na2S (at natural pH) improves both copper and gold metallurgy considerably. 

Bulatovic, S.M., An Investigation of the Recover of Copper and Gold from Igarape Bahia Oxide Copper-Gold Ores, Report of Investigation LR4533, 1997. 

An even more serious problem can arise when dissolved species expected to predominate at high temperatures are undetectable at 25°C or are only present at concentrations which are too low for them to be adequately characterized thermodynamically. Examples are certain transition metal chloro-complexes (9,10) and mixed complexes of such metals with hydroxide and another ligand (11,12). Thus it seems that chloride complexing so alters the aqueous chemistry of copper and gold that supposedly inert gold components in autoclaves are reversibly oxidized by Cull (10) and it is likely that mixed oxine and hydroxy complexes of Fell contribute considerably to the gross under-estimation (by a factor of up to 10 ) of magnetite solubility in oxine (12,14). 

Copper and gold based alloys having giant magneto-resistance properties were produced by Das etal. (1995), by melt spinning from arc melted and cast rods. Typically a portion of a ternary alloy rod having a nominal composition Cu8oCo15Fe5 was... 

A little later Madame Curie and Mademoiselle GHeditsch repeated Cameron and Ramsay s experiments on copper salts, using, however, platinum apparatus. They failed to detect lithium after the action of the emanation, and think that Cameron and Ramsay s results may be due to the glass vessels employed. Dr. Perman has investigated the direct action of the emanation on copper and gold, and has failed to detect any trace of lithium. The transmutation of copper into lithium, therefore, must be regarded as unproved, but further research is necessary before any conclusive statements can be made on the subject. 

EDGAR PHILIP PERMAN "The Direct Action of Radium on Copper and Gold," Proceedings of the Chemical Society, vol. xxiv. (1908), p. 214. 

Silver is probably one of the first metallic elements used by humans. It was known to primitive humans before 5000 bce, at about the time copper and gold were also found in native free forms. Silver jewelry was found in tombs that are over 6,000 years old. 

The United States gets most of its bismuth as a by-product from smelting ores of lead, silver, copper, and gold. It is also recovered from the refining of tin and tungsten ores. 

Typically, coatings most often in use as intermediate layers are silver, nickel, copper, and gold however, silver is used by far the most often. This is so because of the low dissociation temperature of silver oxide, making it relatively easy to obtain clean surfaces. Also, the typical thickness range of electroplates used, in practice, for diffusion welding is about 15 to 40/rm, but thicknesses as great as 130 )um must sometimes be used. A considerable variety of steel types as well as aluminum and a host of other difficult-to-join metals and even beryllium have been and continue to be diffusion bonded with the use of electroplated intermediate layers. 

The Pebble Cu-Au-Mo porphyry deposit (Fig. 1) contains one of the largest resources of copper and gold in the world (NDM 2009). Porphyry deposits typically occur in clusters within subduction-related magmatic belts, suggesting the possibility of multiple occurrences of porphyry-style mineralization near the Pebble deposit, within the southern Kahiltna terrane. In this study, we use USGS spatial data to... 

The Pebble porphyry deposit contains one of the largest resources of copper and gold in the world. The deposit consists of the Pebble West and Pebble East Zones,... 

Henry hoped that alchemical gold might help him to pay state debts. In 1445 Sir Edmund Trafford and Thomas Asheton were duly granted the right to make gold, and coins were actually minted from the product they produced. But their alchemical gold later proved to be an alloy of mercury, copper, and gold. 

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