Reactions of hexafluorobut-2-yne with alkylgold(I) complexes. Properties of intermediate binuclear gold(I)–gold(III) complexes

Abstract

Reactions of alkylgold(I) complexes [AuRL](R = Me, L = PMe₃, PMe₂Ph, or PMePh₂; R = Et, L = PMePh₂) with hexafluorobut-2-yne give first the mixed-oxidation-state complexes [LAu{(F₃C)CC(CF₃)}AuR₂L], which react further to give either the binuclear gold(I) complexes [LAu{(F₃C)CC(CF₃)}AuL] or the products of cis in-sertion of the alkyne into the original Au–C bond, [AuL{(F₃C) CCR (CF₃)}]. The course of this subsequent reaction is dependent on the nature of L and R and on the solvent, and the reaction mechanisms have been investigated. Hydrogen chloride reacts with [LAu{(F₃C)CC(CF₃)}AuMe₂L](L = PMe₃) to cleave the vinylgold(I) bond and give [AuCIL] and [AuMe₂L{(F₃C)CCH(CF₃)}], while metal halides {HgCl₂, [PtX₂(PMePh₂)₂]} react initially to cleave a methylgold (III) bond. Both electrophilic-cleavage and reductive-elimination reactions involving the vinylgold bond occur with retention of stereochemistry about the CC bond. Gold-197 Mössbauer spectra of many of the complexes are reported, and show the presence of both Au^I and Au^III in some complexes.