Silver complexes homoleptic structures

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). 

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. 

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). 

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]. 

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