Crystal structure of phenyl 2,4,5-trichlorobenzenesulfonate

In the title compound, the two aryl rings are oriented gauche to one another, around the sulfonate S—O bond, with a dihedral angle of 72.40 (7)°. In the crystal, molecules are linked via C—Cl⋯π interactions, forming ribbons along the a-axis direction.


Chemical context
The use of arene-sulfonates as leaving groups has been explored in synthetic organic chemistry for quite some time (Crossland et al., 1971;Klá n et al., 2013;Sardzinski et al., 2015). The stability of sulfonate ester leaving groups and the identification of suitable protecting groups for sulfonates has been reported (Miller, 2010). A competitive C-O and S-O bond fission has been reported in the reaction of amine nucleophiles with arene-sulfonates (Um et al., 2004). The basicity of the amine nucleophile and the electronic nature of the substituent on the sulfonyl moiety are responsible for the difference in regioselectivity. We have synthesized various arene-sulfonate analogues in order to investigate the factors responsible for the competition between C-O and S-O bond fission in the reaction with nitrogen nucleophiles (Atanasova et al., 2015;Cooley et al., 2015).
The sulfonamide moiety has found many useful applications in medicinal chemistry (Navia, 2000). Sulfonamides can be synthesized conveniently from the corresponding sulfonyl chloride and amine nucleophiles. In our recent work, we reported on the synthesis and crystal structure of a chiral sulfonamide . The direct synthesis of sulfonamides from arene-sulfonates has been reported (Caddick et al., 2004). Taking advantage of the regioselectivity of C-O vs S-O bond fission, we have explored the use of arene-sulfonates as electrophilic substrates in the synthesis of ISSN 2056-9890 sulfonamides. We are interested in the role of the substituent on the sulfonyl moiety and the basicity of the amine nucleophile on the nucleophilic substitution. As the title compound is of interest in our ongoing effort to investigate the role of the substituent on the sulfonyl moiety in nucleophilic substitution reactions with nitrogen-and oxygen-nucleophiles, we report herein on the synthesis and crystal structure of this electrophilic arene-sulfonate.

Structural commentary
The molecular structure of the title compound is shown in Fig. 1. The two aryl rings are oriented gauche to one another around the sulfonate S1-O1 bond, with a C1-S1-O1-C7 torsion angle of À70.68 (16) . The two rings (C1-C6 and C7-C12) are inclined to one another by 72.40 (7) .

Supramolecular features
In the crystal, molecules are linked by ClÁ Á Á interactions (Table 1 and Fig. 2). These intermolecular interactions range in ClÁ Á Áring centroid distances from 3.525 (1) to 3.972 (1) Å (Table 1). This distance falls near the accepted average as previously noted (Imai, et al., 2008) The molecular structure of the title compound, showing the atom labeling. Displacement ellipsoids are drawn at the 50% probability level. Table 1 Geometric parameters (Å , ) for C-ClÁ Á Á contacts in the title compound..

Figure 2
A view of the various C-ClÁ Á Á interactions (blue dashed lines; see Table 1) present in the crystal lattice of the title compound. H atoms have been omitted for clarity [symmetry codes: (i) Àx + 2, Ày + 1, Àz + 1; (ii) Àx + 1, Ày + 2, Àz + 1; (iii) Àx + 3 2 , y + 1 2 , Àz + 3 'face-on' geometry. The two strong interactions involving atoms Cl1 and Cl2 with the centroid of ring C7-C12 form ribbons propagating along the a-axis direction. Within the ribbon there is also a weaker ClÁ Á Á interaction involving atom Cl3 and the centroid of ring C1-C6. Neighbouring ribbons are linked by a second weak Cl1Á Á Á interaction (Table 1 and Fig. 2), forming layers parallel to the ac plane. There are no other significant intermolecular interactions present in the crystal.

Database survey
The Two recent publications describing the crystal structures of benzopyrimidoazepine derivatives have also noted C-ClÁ Á Á interactions present in the lattice (Acosta et al., 2015;Acosta Quintero et al., 2016). In these examples, the C-ClÁ Á Á interactions are complemented by either C-HÁ Á Á orinteractions between molecules in the solid state.

Synthesis and crystallization
Phenol (0.941g, 10 mmol) was dissolved in 10 ml of chilled dichloromethane. This was followed by the addition of pyridine (1.6 ml, 20 mmol). The resulting solution was cooled in an ice bath under an N 2 atmosphere, followed by the addition of 2,4,5-trichlorobenzenesulfonyl chloride (1.91 g, 10 mmol) portion-wise. The mixture was stirred at 273 K for 30 min and then at room temperature for 12 h. Reaction completion was verified by using TLC analysis. After dilution with 15 ml of CH 2 Cl 2 , the organic phase was washed with H 2 O, brine, and dried over anhydrous Na 2 SO 4 . After the solvent was evaporated the crude product was obtained as a tan solid. The title compound was recrystallized from CH 2 Cl 2 /hexanes to afford colourless needle-like crystals (56% yield, m.p. 380-381 K) suitable for X-ray diffraction analysis.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The positions of all hydrogen atoms were calculated geometrically and refined to ride on their parent atoms: C-H = 0. 95 Å with U iso (H) = 1.2U eq (C).

Phenyl 2,4,5-trichlorobenzenesulfonate
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.