Anionic Derivatives of Perfluorinated Trimethylgold.

The homoleptic compound [PPh4 ][CF3 AuCF3 ] cleanly undergoes photoinduced oxidative addition of CF3 I to afford the organogold(III) derivative [PPh4 ][(CF3 )3 AuI] in good yield and under mild conditions. This compound provides a convenient entry to the chemistry of the perfluorinated (CF3 )3 Au fragment, the properties of which were analyzed with the aid of DFT methods and compared with those of the homologous non-fluorinated (CH3 )3 Au moiety. It was found that reductive elimination of CX3 -CX3 in the former (X=F) requires a much higher energy barrier than in the latter (X=H) and is therefore considerably less favored. This can be considered as one of the main features underlying the significantly higher stability associated to the (CF3 )3 Au fragment and its derivatives. This unsaturated, 14-electron species can be stabilized by coordination of any of the halide ligands, including fluoride. In fact, the whole series of anionic [PPh4 ][(CF3 )3 AuX] complexes (X=F, Cl, Br, I, CN) has now been isolated and conveniently characterized. Evidence for intermolecular decomposition pathways upon thermolysis in the condensed phase is presented.