[2,4,6-Tris(trifluoromethyl)phenyl]gold(I) and -gold(III) Complexes

The complex [Au(Fmes)(tht)] (Fmes = 2,4,6-tris(trifluoromethyl)phenyl or nonafluoromesityl; tht = tetrahydrothiophene) was obtained by reaction of [AuCl(tht)] and Li(Fmes). Monoarylated complexes are readily obtained when the tht ligand is displaced by other neutral ligands, giving [Au(Fmes)L] (L = PPh<INF>3</INF>, P(o-tol)<INF>3</INF>, 2,6-lutidine) or [Au<INF>2</INF>(Fmes)<INF>2</INF>(μ-bipy)] (bipy = 2,2‘-bipyridyl), the latter containing a bridging bipy ligand. tht can also be displaced by halides to give the gold anionic complexes NBu<INF>4</INF>[Au(Fmes)X] (X = Cl, Br, I). [Au(Fmes)(NCMe)] is obtained from the latter by treatment with TlBF<INF>4</INF> in the presence of MeCN. The bis-arylated complexes NR<INF>4</INF>[Au(Fmes)<INF>2</INF>] (R = Et, Bu) were obtained by treatment of NR<INF>4</INF>[AuBr<INF>2</INF>] with excess Li(Fmes). They react with AgBF<INF>4</INF> and 4-methylpyridine to give [Ag(4-Mepy)<INF>2</INF>][Au(Fmes)<INF>2</INF>]. Oxidative addition of halogens to the monoarylated NBu<INF>4</INF>[Au(Fmes)X] and the bis-arylated NR<INF>4</INF>[Au(Fmes)<INF>2</INF>] gives the gold(III) complexes NBu<INF>4</INF>[Au(Fmes)X<INF>3</INF>] and NR<INF>4</INF>[trans-Au(Fmes)<INF>2</INF>X<INF>2</INF>], respectively. The structures of the bis-arylated gold(I) and -(III) complexes NBu<INF>4</INF>[Au(Fmes)<INF>2</INF>] and NEt<INF>4</INF>[trans-Au(Fmes)<INF>2</INF>I<INF>2</INF>] were determined by X-ray diffraction. An analysis of nonbonded distances and torsion angles suggests that steric repulsion of neighboring CF<INF>3</INF> groups is reduced by mutual rotation of the Fmes rings in the former complex but by rotation of the CF<INF>3</INF> groups themselves in the latter (in which the Fmes rings are exactly coplanar).