Trifluoromethylation of [AuF 3 (SIMes)]: Preparation and Characterization of [Au(CF 3 ) x F 3-x (SIMes)] (x=1-3) Complexes.

Trifluoromethylation of [AuF ₃ (SIMes)] with the Ruppert-Prakash reagent TMSCF ₃ in the presence of CsF yields the product series [Au(CF ₃ ) _x F _3-x (SIMes)] (x=1-3). The degree of trifluoromethylation is solvent dependent and the ratio of the species can be controlled by varying the stoichiometry of the reaction, as evidenced from the ¹⁹ F NMR spectra of the corresponding reaction mixtures. The molecular structures in the solid state of trans-[Au(CF ₃ )F ₂ (SIMes)] and [Au(CF ₃ ) ₃ (SIMes)] are presented, together with a selective route for the synthesis of the latter complex. Correlation of the calculated SIMes affinity with the carbene carbon chemical shift in the ¹³ C NMR spectrum reveals that trans-[Au(CF ₃ )F ₂ (SIMes)] and [Au(CF ₃ ) ₃ (SIMes)] nicely follow the trend in Lewis acidities of related organo gold(III) complexes. Furthermore, a new correlation between the Au-C _carbene bond length of the molecular structure in the solid state and the chemical shift of the carbene carbon in the ¹³ C NMR spectrum is presented.
(© 2020 The Authors. Published by Wiley-VCH GmbH.)