Silver complexes alkyl, alkenyl, aryls

Synthesis and Properties of Alkyl, Alkenyl, Aryl, and Related Complexes of Silver 197... 

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... 

In general, the syntheses of these complexes are achieved through (i) nucleophilic addition/substitution reactions of silver(i) fluoride or (ii) transmetallation reactions with other metal alkyl, alkenyl, and aryl complexes. 

A wide range of ligands of the type RXCH2C02H where R = alkyl, alkenyl or aryl and X = S, Se or Te have been reacted with silver ions and thermodynamic data for some representative examples are given in Table 49.358,359 The silver-selenium complexes were found to be more stable than their silver-sulfur analogues as a result of both larger favourable enthalpy and smaller unfavourable entropy changes. 

Trani-allylstannylation is possible with ZrC as a Lewis acid catalyst, reported by Yamamoto and coworkers, also in 1996 (Scheme 5.7.4). Varions terminal alkynes such as aryl-, alkyl-, alkenyl-, or non-substituted acetylenes undergo the reaction with non- or methyl-substituted allylstannanes. Recently, silver complexes were also found to be effective as catalysts for the intra-molecular allylstannylation of alkynes (Scheme 5.7.5). The silver complex is considered to activate the triple bond, giving a cyclo-propylmethylidene or an alkenyl complex as an intermediate. Similar intra-molecular allylstannylations, but with yn-selectivity are known to proceed in the presence of a Pd(0) or an InCls catalyst. 

---