Silver lll Complexes

The first air-stable silver(lll) complex was reported by Furuta et al. (22) in 1999, who synthesized and characterized a silver(lll) complex with 5,10,15,20-tetraphenyl-2-aza-carbaporphyrin (nctpp) as the supporting ligand. The crystal structure shows an inequivalence in the Ag—N bonds and the Ag—C bond, which reflects the asymmetric nature of the porphyrin. Later, the same group reported another silver(lll) complex with ethoxy-5,10,15,20-tetrapentylflorophenyl-3,7-diaza-21,22-dicarbaporphyrin [(n2cp)2l as the supporting ligand (Fig. 3) (23). 

As stated previously, the silver(III) state is stabilized by the electron-rich nature of the ligand in addition to the cavity size contribution. The silver(III) center may easily obtain an electron from the ligand to form a ligand radical, which satisfies the metal ion s high electrophilicity. This finding may explain why in some silver(lll) complexes the silver(II) and (III) states can switch reversibly. Whether this property of silver can be utilized in oxidation catalysis the way iron and manganese porphyrin systems were used still has to be seen (27-30). 

NMR and ESR spectroscopy applied to gold and silver compounds 69 A. NMR Applied to Silver(l) and Silver(lll) Complexes 1. Direct and indirect detection of109Ag and 107Ag... 

A number of well-defined crystalline complexes of silver(III) have been described.496 In particular, biguanides, substituted biguanides, ethylenebis(biguanide) and piperazine dibiguan-ide have been found to complex and stabilize silver(lll). 

The electrocatalytic reaction starts with electron transfer from p-phenylenedi-amine to the cobalt(lll) complex via the silver at a high reaction rate. A competitive reaction involving the oxidative formation of silver halide then begins. This silver halide may be reduced by p-phenylenediamine, which is thus is oxidized directly by the cobalt(III) complex and also by the silver halide formed by the oxidation of silver. 

The photochemical behaviour of other halogenated systems such as phosgene have also been investigated on silver(lll) either as monolayers or multilayers. The UV irradiation of this system brings about C—Cl bond fission. The Cl remains chemisorbed to the surface while the CO is desorbed. Again, the data collected suggest that the mechanism involves excitation of an adsorbate/substrate complex. There is evidence that the silver has a catalytic effect with the onset of the reaction red-shifted by 2.6-2.8 eV from the gas... 

B. Complexes of Silver(l) and Silver(lll) with Perfluoroalkyl Ligands... 

Metal complexes have a variety of stractures. Silver complexes are often linear beryllium complexes are usually tetrahedral iron forms a carbonyl compound that has a trigonal bipyramidal structure cobalt(lll) complexes are octahedral and tantalum forms an eight-coordinated fluoride complex (Figure 3.1). Although a variety of coordination numbers and structures have been observed in metal complexes, the only common coordination numbers are four and six the common structures corresponding to these coordination numbers are tetrahedral and square planar, and octahedral, respectively. In studying metal complexes, it soon becomes clear that the octahedral structure is by far the most common of these configurations. 

Pyridine-bridged bisimidazolium salts also afforded the preparation of dimetallic Rh(l) species by transmetallation from a silver(l)-NHC complex and deprotonation with a weak base. A pincer pyridine-bis-NHC Rh(lll) complex 330 was obtained from the reaction of the corresponding bisimidazolium salt and [Rh(/r-Cl)(cod)]2 in the presence of... 

Silver, lead, copper(l). and thallium(I) thiocyanates are insoluble and mercuiy(II), bismuth, and tm(II) thiocyanates slightly soluble. All of these, are soluble in excess of soluble (e.g., ammonium) thiocyanate, forming complexes. Iron(III) thiocyanate gives a blood-red solution, used in detecting either Fe(lll) or thiocyanate in solution, and is extracted from water by amyl alcohol. It is not formed in the presence of fluoride, phosphate and other strongly complexing ions,... 

Peracetylated glucose, brominated in the 1-position, was reacted with V-methylimi-dazole to yield the corresponding carbohydrate functionalised imidazolium salt [114], Reaction with silver(l) oxide and subsequently with [Cp lrCyj yields the silver(I) and iridium(lll) NHC complexes, respectively (see Figure 6.47). The structural parameters of the Cp lr(NHC) complex are similar to those of analogous Cp lr(NHC) complexes featuring nonfunctionalised carbenes [115,116]. 

Interaction of the 3 2 complex with iron(lll) chloride and calcium oxide, mercury oxide or silver oxide was usually too violent for preparative purposes, but zinc oxide was satisfactory. Reaction with water was violent. 

F/13 C 68°F/20°C (80%) 72°F/22°C (60%) 79°F/26X (40%)]. Reacts, possibly violently, with strong oxidizers, bases, acetic anhydride, acetyl bromide, acetyl chloride, aliphatic amines, bromine pentafluoride, calcium oxide, cesium oxide, chloryl perchlorate, disulfuryl difluoride, ethylene glycol methyl ether, iodine heptafluoride, isocyanates, nitrosyl perchlorate, perchlorates, platinum, potassium-iert-butoxide, potassium, potassium oxide, potassium peroxide, phosphorus(lll) oxide, silver nitrate, silver oxide, sulfuric acid, oleum, sodium, sodium hydrazide, sodium peroxide, sulfinyl cyanamide. tetrachlorosilane, i-tri-azine-2,4,6-triol, triethoxydialuminum tribromide, triethylaluminum, uranium fluoride, xenon tetrafluoride. Mixture with mercury nitrate(ll) forms explosive mercury fulminate. Forms explosive complexes with perchlorates, magnesium perchlorate (forms ethyl perchlorate), silver perchlorate. Flow or agitation of substance may generate electrostatic charges due to low conductivity. 

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