Trifluoromethylation of [AuF3(SIMes)]: Preparation and Characterization of [Au(CF3)xF3−x(SIMes)] (x=1–3) Complexes

Abstract

Trifluoromethylation of [AuF3(SIMes)] with the Ruppert–Prakash reagent TMSCF3 in the presence of CsF yields the product series [Au(CF3)xF3−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 19F NMR spectra of the corresponding reaction mixtures. The molecular structures in the solid state of trans-[Au(CF3)F2(SIMes)] and [Au(CF3)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 13C NMR spectrum reveals that trans-[Au(CF3)F2(SIMes)] and [Au(CF3)3(SIMes)] nicely follow the trend in Lewis acidities of related organo gold(III) complexes. Furthermore, a new correlation between the Au−Ccarbene bond length of the molecular structure in the solid state and the chemical shift of the carbene carbon in the 13C NMR spectrum is presented.