Gold trifluoromethyl complexes

Abstract

This article reviews the synthesis, reactivity and applications of gold trifluoromethyl complexes, which are the only isolated perfluoroalkyl complexes of gold. The most reported examples are neutral Au(i) complexes of the type [Au(CF3)L], whereas only two Au(ii) trifluoromethyl complexes have been reported, both being diamagnetic and containing a strong Au-Au bond. A number of Au(iii) trifluoromethyl complexes have been prepared by oxidative addition of halogens or iodotrifluoromethane to Au(i) complexes or, in a few cases, by transmetallation reactions. Owing to the limitations of the available synthetic methods, a lower number of examples is known, particularly for the oxidation states (ii) and (iii). Gold trifluoromethyl complexes present singular characteristics, such as thermal stability, strong Au-C bonds and, in some cases, reactive α-C-F bonds. Some of the Au(iii) complexes reported, show unusually easy reductive elimination reactions of trifluoromethylated products which could be applied in the development of gold-catalyzed processes for the trifluoromethylation of organic compounds.

(CF3)3Au as a Highly Acidic Organogold(III) Fragment

“…[21] With regard to gold chemistry,t he CF 3 group was first introduced by Puddephatt et al in the 1970s. [23] We have recently found ac onvenient entry to the chemistry of the (CF 3 ) 3 Au fragment, whichh as emerged as as tereochemically robust moiety with am arked reluctance to undergo reductive elimination of CF 3 ÀCF 3 . [23] We have recently found ac onvenient entry to the chemistry of the (CF 3 ) 3 Au fragment, whichh as emerged as as tereochemically robust moiety with am arked reluctance to undergo reductive elimination of CF 3 ÀCF 3 .…”

“…in the 1970s . Since that early work, the study of trifluoromethyl gold derivatives has aroused continued interest, but only recently has it developed into a hot research topic …”

An Organogold(III) Difluoride with a trans Arrangement

“…[7,8] As far as we know,t he single example of organogold(III) difluoride with trans geometry is given by the anion [trans-(CF 3 ) 2 AuF 2 ] À ,w hich was detected in solution along with the trifluoride [CF 3 AuF 3 ] À and various other species,b ut could not be separated. [12] Now we report on an efficient and stereoselective synthesis of the elusive species [trans-(CF 3 ( 1). [12] Now we report on an efficient and stereoselective synthesis of the elusive species [trans-(CF 3 ( 1).…”

A catalytic fluoride-rebound mechanism for C(sp 3 )-CF 3 bond formation

“…The successful development of this advance depended on mechanistic investigation of an unexpected trifluoromethylated compound observed upon treatment of complex 1a with B(C 6 F 5 ) 3 ( 2 ) (Fig. 2A), namely the formal product of C(sp 3 )-CF 3 reductive elimination from the gold center (20, 21). …”