Herein we report the mechanism of
oxidative addition of CF3I to Au(I), and remarkably fast
Caryl–CF3 bond reductive elimination
from Au(III) cations. CF3I undergoes a fast, formal oxidative
addition to R3PAuR′
(R = Cy, R′ = 3,5-F2-C6H4,
4-F-C6H4, C6H5, 4-Me-C6H4, 4-MeO-C6H4, Me; R = Ph,
R′ = 4-F-C6H4, 4-Me-C6H4). When R′ = aryl, complexes of the type R3PAu(aryl)(CF3)I can be isolated and characterized. Mechanistic
studies suggest that near-ultraviolet light (λmax = 313 nm) photoinitiates a radical chain reaction by exciting CF3I. Complexes supported by PPh3 undergo reversible
phosphine dissociation at 110 °C to generate a three-coordinate
intermediate that undergoes slow reductive elimination. These processes
are quantitative and heavily favor Caryl–I reductive
elimination over Caryl–CF3 reductive
elimination. Silver-mediated halide abstraction from all complexes
of the type R3PAu(aryl)(CF3)I results
in quantitative formation of Ar–CF3 in less than
1 min at temperatures as low as −10 °C.