Nitrogen gold clusters

The details given above gather the features that the nonconventional N-H- -Au bond formed between adenine and the triangle three-gold cluster shares with the conventional ones. In these bonds, the nitrogen atom of adenine is a H-bond donor and Au plays a role of a nonconventional H-bond acceptor. 

Formation of Mixed-Ligand Tetranuclear Gold(l) Nitrogen Clusters... 

This type of interaction is most commonly present in complexes containing tetracyanoaurate(III) anions, which can be present in the solid state in different association degrees. The simplest one is found in ]Cu(bipy)(H20)2 Au(CN)4 o.5][Au (CN)4]15 (bipy = 2,2 -bipyridine) [48] or in [ Cu(tmeda)( a-OH) 2Au(CN)4][Au(CN)4] (tmeda= N,N,N, N -tetramethylethylenediamine) [49], where part of the [Au(CN)4 anions form a linear trimeric anionic cluster via Au - N van der Waals interactions of the nitrogen atoms of two cyano groups trans to the gold(III) centers of two adjacent anions (Figure 5.24a). The interacting distances, 3.052(9) or 3.062 A, respectively, are... 

Radiolysis has been used successfully in order to synthesize various noble (such as silver, gold and platinum) and non-noble (such as nickel and iron) metal nanoparticles in aqueous solution and also in other solvents such as alcohols. Due to their relatively low redox potential compared to that of the bulk, metal clusters can be oxygen-sensitive. However, the deoxygenation (by bubbling with an inert gas such as argon or nitrogen) of the solutions prior to irradiation and their study under inert atmosphere prevent their oxidation. Moreover, since water radiolysis leads to the formation of protons in addition to that of hydrated electrons, radio-induced acidification of the medium may lead to non-noble metal clusters corrosion. Therefore, to avoid the oxidation by protons, the solutions can be prepared in slightly basic medium. 

This section includes selected examples of electrochemistry of gold and silver complexes with other ligands and structural types that were not included in previous sections. We have also included a list of references divided into the following areas that can be consulted for additional information sulfur- and nitrogen-containing macrocycles , porphyrins " and clusters . 

These chains are linked at each end by a nitrogen atom. Cryptands, like the crown ethers, can form coordination complexes with ions that can tit into the cavity formed by the open three-dimensional structure, i.e. they can cryptate the ion. Various types of cryptand have been produced having both spherical and cylindrical cavities. The cryptands have the same kind of properties as the crown ethers and the same uses. In general, they form much more strongly bound complexes and can be used to stabilize unusual ionic species. For example, it is possible to produce the negative Na ion in the compound [(2,2,2)-cryptand-Na] Na , which is a gold-coloured crystalline substance stable at room temperature. Cluster ions, such as Pbs ", can be similarly stabilized. 

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