N-(4-Chlorophenyl)-1,1,1-trifluoro-N-(trifluoromethylsulfonyl)methanesulfonamide

The title molecule, also called 4-chloro-N,N-bis(trifluoromethanesulfonyl)aniline, C8H4ClF6NO4S2, has non-crystallographic twofold symmetry with the pseudo-axis aligned along the Cl—C⋯C—N backbone of the molecule: the SO2CF3 residues lie to either side of the benzene ring. In the crystal, the presence of C—H⋯O contacts lead to the formation of a sequence of 12-membered {⋯HC2NSO}2 synthons within a supramolecular chain aligned along [101].

The title molecule, also called 4-chloro-N,N-bis(trifluoromethanesulfonyl)aniline, C 8 H 4 ClF 6 NO 4 S 2 , has non-crystallographic twofold symmetry with the pseudo-axis aligned along the Cl-CÁ Á ÁC-N backbone of the molecule: the SO 2 CF 3 residues lie to either side of the benzene ring. In the crystal, the presence of C-HÁ Á ÁO contacts lead to the formation of a sequence of 12-membered {Á Á ÁHC 2 NSO} 2 synthons within a supramolecular chain aligned along [101].
The use of the EPSRC X-ray crystallographic service at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil). Comment N,N-Bis(trifluoromethanesulfonyl)aniline derivatives find use in synthetic chemistry such as mild triflating reagents (Zeller, 2001;Wulff et al., 1986). Following a literature procedure to p-ClC 6 H 4 NHSO 2 CF 3 , using p-ClC 6 H 4 NH 2 , (F 3 CSO 2 )O and Et 3 N in CH 2 Cl 2 at 213 K, a little of the di-substituted compound, p-ClC 6 H 4 (NSO 2 CF 3 ), (I), was isolated as a side-product (Greenfield & Crosanu, 2008;Deprez et al., 1995). Compound (I) has been reported previously (Laali et al., 2007) and the X-ray structure determination is reported herein.
In (I), the SO 2 CF 3 groups occupy approximately orthogonal positions to either side of the aromatic ring: the C3/C4/N1/ S1, S2 torsion angles are 77.44 (17) and -101.55 (15) °, respectively; the dihedral angle formed between the benzene ring and NS 2 group is 78.13 (6) °. The CF 3 groups lie to either side of the molecule and fold back over the benzene ring so that, overall, the molecule has non-crystallographic 2-fold symmetry when viewed down the Cl1-C1-C4-N1 axis.

Experimental
To a cooled (213 K) solution of p-ClC 6 H 4 NH 2 (11.5 g, 9.0 mmol) and triethylamine (1.50 ml; 10.8 mmol, 1.20 eq.) in CH 2 Cl 2 (40 ml) was slowly added a solution of trifluoromethanesulfonic anhydride (2.40 ml; 13.5 mmol, 1.50 eq) in CH 2 Cl 2 (40 ml). After the mixture was stirred at 213-223 K for 1 h, water (30 ml) was added. The mixture was allowed to warm to room temperature, and the organic layer was decanted, washed with water, dried, and evaporated. The products, N-

Refinement
The C-bound H atoms were geometrically placed (C-H = 0.95 Å) and refined as riding with U iso (H) = 1.2U eq (C).  Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.