Oxidative addition in the coupling of alkylgold(I) with alkyl halides

MeAu(PPh₃) reacts with MeI to afford C₂H₆ and I(PPh₃)Au by a multi-step mechanism involving: (i) oxidative addition to form an intermediate Me₂AuI(PPh₃) species, which (ii), undergoes iodide-methyl exchange with another MeAu(PPh₃) species to afford Me₃Au(PPh₃), followed by (iii), reductive elimination of C₂H₆ and reformation of MeAu(PPh₃). The more reactive trime thylphosphine derivative also readily undergoes (i) oxidative addition and (ii) methyl exchange. However, Me₃Au(PMe₃) is more stable than the PPh₃ analog and does not undergo (iii) reductive elimination. Instead, it is involved in (iv), a further very slow reaction with IAu(PMe₃) and MeI to afford Me₂ AuI(PMe₃) in high yields. C₂H₅Au(PPh₃) specifically affords n-C₄H₁₀ at 0° in MeI. Reactions of other alkylgold(I) complexes with alkyl halides are also reported, and fit into a general mechanistic pattern desribed by reactions (i) – (iv).