Trifluoromethylation of [AuF3(SIMes)]: Preparation and Characterization of [Au(CF3)xF3-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 trifluoro-methylation 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 lengths of the molecular structure in the solid state and the chemical shift of the carbene carbon in the 13 C NMR spectrum is presented.