sp–sp3 Coupling reactions of alkynylsilver cations, RC
CAg2+ (R = Me and Ph) with allyliodide†
Abstract
Alkynylsilver CAg2+ (where R = Me and Ph) have been prepared in the gas phase using multistage
CAg2+, via a facile decarboxylation of the RC
CCO2Ag2+ precursor; (ii) ESI of silver acetylides, RC
CAg, which yields a cluster of the type, [(RC
CAg)12Ag2Cl]+. Regardless of the method of preparation, these alkynylsilver
CAg2+, undergo ion-molecule reactions with
CCH2CH
CH2)Ag]+. The
CCH2CH
CH2)Ag]+ was compared to that of an authentic sample of the silver adduct of 5-phenyl-1-penten-4-yne. Both ions fragment to yield Ag+ and the radical
CCH2CH
CH2+˙, confirming that C–C bond coupling has taken place in the gas phase. DFT calculations were carried out on these C–C bond coupling reactions for the system R = Me. The reaction is highly exothermic and involves the initial coordination of the allyliodide to both silver atoms, with the iodine coordinating to one atom and the alkene moiety coordinating to the other. The overall mechanism of C–C bond coupling involves oxidative addition of the allyliodide followed by reductive elimination of RC
CCH2CH
CH2, to ultimately yield two sets of reaction products: (i) Ag2I+ and RC
CCH2CH
CH2; and (ii) [(RC
CCH2CH
CH2)Ag]+ and AgI.