Synthesis of Au(I) Trifluoromethyl Complexes. Oxidation to Au(III) and Reductive Elimination of Halotrifluoromethanes

Abstract

Au(I) trifluoromethyl complexes [Au(CF3)L] (L = N-heterocyclic carbene (NHC), isonitrile, phosphine, P(OMe)3) and [Au2(CF3)2­(μ-dppe)] are prepared by reaction of [Au(X)L] (X = Cl, I) or [Au2Cl2­(μ-dppe)], respectively, with AgF and Me3SiCF3. The analogous reaction of PPN[Au(C6F5)­Cl] (PPN+ = [Ph3PNPPh3]+) gives a mixture of complexes of the type PPN[Au(CF3) x ­(C6F5)2–x ] (x = 0, 1, 2). Single crystals of the new complex PPN[Au(CF3)­(C6F5)] are obtained by liquid diffusion from this mixture, and its crystal structure was determined by X-ray diffraction. Acyclic diaminocarbene complexes [Au(CF3)­{C(NEt2)­(NHR)}] (R = t Bu, 2,6-dimethyl­phenyl) are obtained by reaction of [Au(CF3)­(CNR)] with NHEt2. Oxidation of the NHC complex [Au(CF3)­(IPr)] (IPr = 1,3-bis(2,6-diiso­propyl­phenyl)­imidazol-2-ylidene) with PhICl2, Br2, I2 or ICl affords [Au(CF3)(X)­(Y)(IPr)] (X = Y = Cl, Br I; X = Cl, Y = I). The dicloro, dibromo, and chloro(iodo) complexes are stable in solution in the dark. In contrast, the diiodo complex is unstable and decomposes to [AuI(IPr)] and ICF3. Under photoirradiation, complexes [Au(CF3)(X)­(Y)(IPr)] undergo reductive elimination to give YCF3 and [AuX(IPr)] (X = Y = Cl, Br; X = Cl, Y = I).

Gold trifluoromethyl complexes

“…The only higher gold perfluoroalkyl reported, [Au(C 2 F 5 )(PEt 3 )], was detected by NMR spectroscopy in the mixture of compounds resulting from the reaction between [Au(CF 3 )(PEt 3 )] and IC 2 F 5 , although it was not isolated. 108 Recently, we reported the synthesis of a family of Au(I) trifluoromethyl complexes by the reaction of Au(I) chloro complexes with AgF and Me 3 SiCF 3 (Scheme 4). 98 In contrast, the complex [Au(OH)(IPr)] (IPr = 1,3bis(2,6-diisopropylphenyl)imidazol-2-ylidene) 107 did not react with Me 3 SiCF 3 at room temperature or at 80°C.…”

“…58 The reactions of Me 3 SiCF 3 with [Au(OR)L] (R = CH(CF 3 ) 2 , L = PMe 3 , PCy 3 , PPh 3 , PMe 2 Ph; R = Ph, L = PCy 3 , PPh 3 ) were used by Komiya and coworkers to prepare a series of trifluoromethyl complexes of the type [Au(CF 3 )( phosphine)] (Scheme 3). 81 lated and used for a crystal structure determination (Fig. 108 Recently, we reported the synthesis of a family of Au(I) trifluoromethyl complexes by the reaction of Au(I) chloro complexes with AgF and Me 3 SiCF 3 (Scheme 4).…”

“…81 The and [AuI(PR 3 )] have been also reported (Scheme 13). These complexes are thermally stable except in the case of trans-[Au(CF 3 )I 2 (IPr)], which reductively eliminates ICF 3 even at low temperature.…”

“…122 Recently, Menjón and coworkers described the synthesis of this complex by the reaction of AuCl 3 , Me 3 SiCF 3 and CsF (Scheme 16). 81 Scheme 13 Oxidative addition of ICF 3 to Au(I) trifluoromethyl complexes. Photochemical or thermal reductive eliminations of halotrifluoromethanes.…”

“…61Scheme 5 Synthesis of Au(I) trifluoromethyl complexes containing NAC ligands by the reaction of (trifluoromethyl)isocyanide complexes with Et 2 NH 81. 81 Scheme 6 Synthesis and fluoride abstraction reactions of [Au-(CF 3 ) 2 ] − .…”