Homoleptic complexes silver

Ag(I) is a d10 ion and, like Au(I), can be two-, three- or four-coordinate with appropriate ligands. The idealized geometries are linear, trigonal planar and tetrahedral, but distortions from the ideal are observed in the solid state and in non-homoleptic complexes where greater silver s character is conferred on the bonds to selected elements. The chemical shift values generally increase with coordination number, other things being equal,... 

A. J. Arduengo, H. V. R. Dias, J. C. Calabrese, F. Davidson, Organometallics 1993,12, 3405-3409. Homoleptic carbene-silver(I) and carbene-copper(I) complexes. 

The chemistry of silver(I) with crown thioethers has developed in the last years,1094,1095 but now numerous examples with a great variety of ligands have been reported. The first homoleptic silver compounds have been described with 1,4,7-trithiacyclononane ([9]aneS3), [Ag([9]aneS3)2]OTf (168), which is octahedral and shows a reversible oxidation assigned to the Ag1/Ag11 couple,1096,1097 and the trimeric species [Ag3([9]aneS3)3]3+ (169).1097 The complexes... 

Examples of silver(l) alkyl and alkenyl (including aryl) complexes have been known from as early as 1941 6-9 however, the number of examples is fairly limited with respect to that of the heavier congeners, copper(l) and gold(l). Such a phenomenon can readily be attributed to the relatively low stability of this class of complexes, both photochemically and thermally. Simple homoleptic alkyl and alkenyl complexes of silver(i) are known to be very unstable under ambient temperature and light, and successful isolation of this class is fairly limited and mainly confined to those involving perfluoroorganics.10 The structures and the metal-carbon bond-dissociation energies for... 

A homoleptic methylene-bridged bis(carbene) dinuclear silver(i) complex, 55, was isolated in 81% yield from a two-step reaction, as shown in Scheme 13.100 The structure of 55 reveals a boat conformation with the two methylene groups protruding away from the Ag2 core in one direction. The Ag-C distances of 2.081(2)-2.095(2) A were in the normal range for silver(i) TV-heterocyclic carbene complexes, while an uncommonly short intramolecular Ag-Ag contact of 3.2039(3) A was observed in the homoleptic silver(i) carbene complexes. 

Although reports on silver(i) cr-alkynyl complexes have appeared for more than a century, the number of examples was still very limited prior to the past decade, and many of them were referred to as insoluble homoleptic polymeric [Ag(C=CR)]oo. Molecular alkynylsilver(i) complexes were often heteroleptic in nature and were achieved commonly through the stabilization by an extra coordination with strong cr-donor ligands such as amines, phosphines, and arsines. 

A very interesting amido functionahsed carbene was prepared by Legault et al. [116] from A-mesitylimidazole and 0-(2,4-dinitrophenyl)hydroxylamine, an electrophilic ami-nation reagent [117]. The exo-amino group is subsequently acylated to afford a zwitterionic amido functionalised carbene (see Figure 4.38). Reaction with silver(l) acetate and sodium carbonate [a rare variant of the silver(I) oxide method] yields the silver(l) carbene complex as a dimer with a Ag-Ag bond. The silver(l) carbene complex can be used as a carbene transfer reagent to synthesise the homoleptic monomeric copper(Il) carbene complex. 

The position of [Ag(bpy)2] salts is slightly clearer. Although crystal structural determinations indicate weak interactions between [Ag(bpy)2l cations and anions or solvent molecules, the cations can be regarded as homoleptic [Ag(bpy)2] complexes (1, 617, 728). Reddish-brown salts of [Ag(bpy)2l are readily obtained by electrochemical, persulphate, or ozone oxidation of either [Ag(bpy)2l or silver(I) salts in the presence of excess bpy (543, 621, 629, 641, 926, 967). The salt [Ag(bpy)2]fS03Fl2 is prepared by the reaction of bpy with Ag(S03F)2, obtained from the direct reaction of silver with S2O6F2 (541, 542). 

Dinuclear complexes were obtained by reacting some binary copper(I) and silver(I) homoleptic pyrazolate complexes with neutral ligands. The trimeric [Cu(dmpz)]3 (23) readily reacted with phen or RNC (R = cyclohexyl) to give the doubly bridged species [(phen)Cu(/i-dmpz)2Cu(phen)], 32, (49) or [(RNC)Cu(/t-dmpz)2Cu(RNC)], 33 (50). The dimeric nature of 32 was argued from its spectroscopic and chemical properties, while 33 was characterized by an X-ray crystal structure analysis (50). 

Only a few complexes containing Ce(IV)-carbon bonds have been structurally characterized so far. Salt metathesis reactions utilizing mixed alkoxide nitrate Ce(IV) precursors [Eq. (63)] [311], as well as the oxidative salt elimination of K[Ce(COT)]2 ate complexes with silver iodide, led to isolable organocerium(IV) species [Eq. (64)] [80e]. The oxidation of the homoleptic Ce(III) alkoxide Ce(OCrBu3)3 with benzoquinone yielded a dinuclear heteroleptic Ce(IV) complex [Eq. (65)] [312]. 

Homoleptic silver complexes [Ag(L-L)2]X (where X = BF4 L-L = o-C6H4(EMe)2 E = S, Se, Te) have been prepared from the ligand with anhydrous AgBp4 in acetone . ... 

A series of homoleptic copper(i), silver(i), and gold(i) complexes of two bisphosphine ligands l,2-bis(diphenylphosphino)benzene, dppb bis[2-(diphenylphosphino)phenyl]ether, POP has been studied to demonstrate that these species are very low emissive in solution but highly luminescent in the solid state. In particular, the silver and copper complexes afford quite broad electroluminescence spectra with white light emission when used in the fabrication of light-emitting devices. ... 

More recently, Albercht and coworkers have reported a study on the disproportionation of [Au(trz)Cl] (trz = 1,2,3-triazolylidene) complexes in the presence of silver salts to afford homoleptic and heteroleptic [Au(trz)(L)][X]... 

The synthesis of the homoleptic platinumfll) aqua-dication via halide abstraction illustrates the utility of silver salts in such processes. For many years workers were unable to prepare [Pt(H20>4]2+ and Livingstone contended that the complex does not form. However, in 1976 Elding prepared [Pt(H20)4]2+uia chloride abstraction with a silver salt, demonstrating that when K2[PtCl4] is reacted with an excess of silver perchlorate in water, flie reaction proceeds as shown in Scheme 3.7 ... 

In Chapter 3 we considered methods of formation of solvento-complexes and illustrated the various ways these compounds are prepared. Halide abstraction techniques that utilize silver salts are commonly employed in the synthesis of mixed-ligand solvento-complexes and such techniques are used also for the transformation of halide complexes into homoleptic solvento-complexes. 

There are many examples of the synthesis of homoleptic solvento-complexes by halide abstraction from compounds containing both coordinated halides and solvento-ligands. Palladium chloride is known to dissolve in nitriles, dimethylformamide, and dimethyl sulfoxide with the formation of complexes of the type [PdCl2(solv)2] which can be isolated as solids.3 The reaction of [PdCl2(RCN)2] with an excess of silver ions s is a convenient method for the synthesis of [Pd(RCN)4]2+. The tetra(acetonitrile)-platinum(II) and tetra(propionitrile)platinum(II) salts have been prepared in this way (Scheme 4.6). Wayland and Schramm have synthesized homoleptic palladium(II) complexes with DMSO, DMF, and DMAA in a similar manner. 

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