Alkynyl silvers

A wide variety of organoalkynyl derivatives of cotarnine hydrochloride, a cyclic iminium salt with rich biological activity, were prepared from the direct alkynylation of cotarnine hydrochloride using silver(l) alkynyls.180 Substituted enynes were prepared from the coupling reactions of silver alkynyls with the palladium allyl intermediates, which was 

Synthesis and Properties of Alkynyl and Related Complexes of Silver 226 

Silver(m) Complexes with Alkyl, Alkynyl, and Cyano Ligands 241 

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. 

Figure 42 Decanuclear silver(i)—rhenium(i) alkynyl complexes 95a-d.

Syntheses and luminescence studies of mixed-metal gold(I)-copper(l) and -silver (I) alkynyl complexes. The tuming-on of emission upon d metal ion encapsulation. Dalton Transactions, 1830-1835. 

It has been demonstrated by 1H, 13C, and 109Ag NMR that a 7r-alkyne-Ag complex and then an alkynyl silver are formed in situ from alkyne and silver salt under conditions related to those used for Ag-catalysed alkynylation or for Ag/Pd-catalysed sp-sp2 cross-coupling reactions.142 These observations have prompted a rationale of the mechanisms of these reactions. 

Silver(I) Inflate and copper(I) triflate can be applied as catalysts A representative example is the preparation of alkynyl tosylates by the catalytic decomposition of alkynyl lodonium salts in the presence of these salts [727] (equation 67) 

The title reactions refer to alkylation reactions using alkynyl silvers as reagents. It seems that no catalytic version has so far been reported, and only a few examples of stoichiometric reactions are known.8 

Interestingly, the first catalytic version of such nucleophilic additions of alkynyl silvers to aldehydes has been described." Indeed, silver chloride in the presence of tricyclohexylphosphine and mild bases such as ethyldiisopropylamine catalyzed the addition of terminal alkynes to aldehydes in good to high yields (Table 10.5). The reaction proved to be almost insensitive to electronic effects however, alkyla-cetylenes were less reactive than arylacetylenes. The solvent had a dramatic effect on the reaction course. Control experiments with preformed phenylethynylsilver showed that both phosphine and water activated the silver acetylide. 

The zinc-cyanide complexes are on the interface of organic and inorganic chemistry. We include them here because of their Zn—C bond. (Perhaps this will encourage thermo-chemical investigations on the isoelectronic alkynylzinc species, much as there has been interest in both cyano and alkynyl silver-containing species. ) The species Zn(CN)2, Zn(CN)3 and Zn(CN)4 have all been thermochemically characterized in aqneons soln-tion by thermometric titration. The enthalpy of reaction values kJmoL are shown for reactions 9-11. 

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