Subject silver complexes

Other transition metals have received much less attention. Complexes of palladium and 2-amino-phenyl-containing formazans have been reported.397 Mercury complexes of tridentate formazans have been studied.398 Silver complexes of tridentate benzothiazolyl-containing formazans have also been studied.399 Recently, alkali and alkaline earth metals have been the subject of many studies. Formazans such as 228 and 229 as well as the macrocyclic 204 have received considerable attention as metal-specific analytical reagents.400-41 1... 

Another approach employing chiral acyclic azomethine ylides was published in two recent papers by Alcaide et al. (85,86). The azomethine ylide-silver complex (51) was formed in situ by reaction of the formyl-substituted chiral azetidinone (50) with glycine (or alanine) in the presence of AgOTf and a base (Scheme 12.18). Azomethine ylides formed in this manner were subjected to reaction with various electron-deficient alkenes. One example of this is the reaction with nitrostyrene, as illustrated in Scheme 12.18 (86). The reaction is proposed to proceed via a two step tandem Michael-Henry process in which the products 52a and 52b are isolated in a... 

This is one approach to the explanation of retention by polar interactions, but the subject, at this time, remains controversial. Doubtless, complexation can take place, and probably does so in cases like olefin retention on silver nitrate doped stationary phases in GC. However, if dispersive interactions (electrical interactions between randomly generated dipoles) can cause solute retention without the need to invoke the... 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

The preparation and reactions of metal cluster ions containing three or more different elements is an area with a paucity of results. The metal cyanides of Zn, Cd (258), Cu, and Ag (259) have been subjected to a LA-FT-ICR study and the Cu and Ag complex ions reacted with various reagents (2,256). The [M (CN) ]+ and [M (CN) +11 ions of copper, where n = 1-5, were calculated to be linear using the density functional method. The silver ions were assumed to have similar structures. The anions [M (CN) +1 of both copper and silver were unreactive to a variety of donor molecules but the cations M (CN) H + reacted with various donor molecules. In each case, where reactions took place, the maximum number of ligands added to the cation was three and this only occurred for the reactions of ammonia with [Cu2(CN)]+, [Cu3(CN)2]+, [Ag3(CN)2]+, and [ Ag4(CN)3]+. Most of the ions reacted sequentially with two molecules of the donor with the order of reactivity being Cu > Ag and NH3 > H2S > CO. 

Yamane T, Davidson N (1962) On the complexing of deoxyribonucleic acid by silver . Biochim Biophys Acta (BBA) 55 609-621, Specialized section on nucleic acids and related subjects... 

The preparation and structural investigation of silver(I) thiourea complexes have been the subject of numerous reports.340 In solution, the formation of stable, mononuclear complexes containing up to four thiourea groups has been proposed and the associated thermodynamic data are collected in Table 47. -342... 

Tetracarbonyl cations [Cr(CO)4(L2)]+, where L2 represents arylphosphines, alkyl, or aryl phosphites, or a bidentate ligand with phosphorus or arsenic donor atoms, have been produced by both chemical and electrochemical means. However, oifly one of these complexes, namely, tra i -[Cr(CO)4(PPh3)2]+, is stable enough to be isolated as the perchlorate salt. Exposure to light and moisture produces tra i -Cr(CO)4(PPh3)2 via disproportionation. Just as easily isolated, but somewhat less sensitive, are the [Cr(CO)3(PR3)3]+ cations. " Oxidation with a silver ion or NO+ converts the /uc-(R3 = Me2Ph, (OMe)3) and mer-(R3 = (OMe)3, (OMe)2Ph, (OPh)3) complexes into Cr products with mer structures. Light and heat promote the formation of reduced wer-Cr(CO)3 (PR3)3. These tetra(carbonyl) and tri(carbonyl) cations have been the subject of ESR spectroscopy and theoretical study. 

Improved reaction. Conia et al. have reported two modifications of the Simmons-Smith reaction which ave improved yields. One is the use of a zinc-silver couple in place of the zinc copper couple. This couple is prepared by adding granular zinc to a stirred hot solution of silver acetate in acetic acid. The mixture is stirred for 30 sec. and the zinc-silver couple formed is isolated by decantation and washed with acetic acid and ether. It is then stabilized by addition of a small amount of silver wool. The second improvement is that the reaction mixture is not subjected to acid hydrolysis. Instead an amine, for example pyridine, is added. This forms the insoluble complexes Znlj-C HsN and ICH jZnl -(C, 115N)j the cyclopropane products are then isolated from the filtrate. 

The only complex having olefinic double bonds alone in the coordination sphere of the silver ion which has been subjected to a complete structural analyses (404) is the bullvalene (532) complex (CioHjo)sAgBF4. The structure consists of discrete (CioHio)3Ag+ cations and BF4 anions (Fig. 12). The three bullvalene molecules in the complex cation are... 

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