Gold-Copper Derivatives

Both complexes emitt in solid state at room temperature 547 nm (max. exc. 397) for the silver complex, and 570 nm (max. exc. 366 nm) for the copper one (Fig. 13). The emissions shift to lower energies when the temperature is lowered to 77 K (567 nm and 594 nm, respectively), suggesting that the 

FIGURE 13. Proposed photophysical model for the [Au2M2(C6F5)4(MeCN)2]n (M=Ag, Cu) complexes. 

Finally, the time-dependent DFT calculations agreed with the experimental results, showing that the transition responsible for the luminescent behavior is that from an antibonding occupied orbital, mainly centered in the gold interacting atoms with a contribution from the heterometals, to a bonding virtual orbital located between the gold and the silver (or copper) centers. 

When the previous reaction is carried out in the same solvent (acetonitrile) with the addition of one equivalent of pyrimidine, the polymeric species [CuAu(C6F5)2(MeCN)(p,2-C4H4N2)] is obtained in high yield.45 In this case, the chain of metals is different from the previous case, and polymerization is produced by covalent copper-pyrimidine bonds with pairs of gold-copper interactions (2.8216(6) A). The environment of the copper centers is tetrahedral, with one acetonitrile molecule occupying the fourth position (Fig. 14). 

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Scheme 8.1 Mixtures of gold and copper derivatives studied.

In the elucidation of the X-ray structure of hCP by the method of isomorphous replacement, gold and mercury heavy atom derivatives were utilized. In the case of the mercury derivative, p-chloromercury-benzoate, the heavy atom bound to the free sulphydryl residue, C221, but for the gold cyanide derivative the gold atom was found to bind in the vicinity of the trinuclear copper cluster. A realistic explanation of this... 

Derivation In ores with platinum, gold, copper, etc. Concentrated ores are dissolved in aqua regia after gold and platinum are removed by chemical treatment, palladium is precipitated by ammonia, followed by hydrochloric acid. After further purification treatment, ignition yields palladium metal. 

The photophysical properties of metal-alkyne materials are rich due to strong metal-ligand orbital overlap and unsaturated n system (16). Photoactive materials can be readily constructed from copper(l) (198-200), rhenium(l) (101, 186, 201-203) platinum(ll) alkynyls (13, 203-219), as well as various gold(l) derivatives (210, 220-226). 

Geminally dimetallated gold-copper complexes derived from carbodi-phosphoranes and phosphinidene-carbene adducts have been prepared... 

Hi) Gold. Whereas the alkyl and aryl complexes of copper and silver are only known in the (1) oxidation state, gold forms derivatives in both the (I) and (III) states. 

A unique method to generate the pyridine ring employed a transition metal-mediated 6-endo-dig cyclization of A-propargylamine derivative 120. The reaction proceeds in 5-12 h with yields of 22-74%. Gold (HI) salts are required to catalyze the reaction, but copper salts are sufficient with reactive ketones. A proposed reaction mechanism involves activation of the alkyne by transition metal complexation. This lowers the activation energy for the enamine addition to the alkyne that generates 121. The transition metal also behaves as a Lewis acid and facilitates formation of 120 from 118 and 119. Subsequent aromatization of 121 affords pyridine 122. 

The name copper and the symbol Cu are derived from the Latin cuprum, after the island of Cyprus, where the Romans first obtained copper metal. The symbols Ag and Au for silver and gold come from the Latin names for these elements argentum... 

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