Synthesis of gold(I)-trifluoromethyl complexes and their role in generating spectroscopic evidence for a gold(I)-difluorocarbene species

Readily prepared and bench-stable [Au(CF ₃)(NHC)] compounds were synthesized by using new methods, starting from [Au(OH)(NHC)], [Au(Cl)(NHC)] or [Au(L)(NHC)]HF ₂ precursors (NHC=N-heterocyclic carbene). The mechanism of formation of these species was investigated. Consequently, a new and straightforward strategy for the mild and selective cleavage of a single carbon/fluorine bond from [Au(CF ₃)(NHC)] complexes was attempted and found to be reversible in the presence of an additional nucleophilic fluoride source. This straightforward technique has led to the unprecedented spectroscopic observation of a gold(I)−NHC difluorocarbene species.