Crystal structure of bis[bis(4-azaniumylphenyl) sulfone] tetranitrate monohydrate

The synthesis and structural determination of bis(4,4′-diammoniodiphenyl)sulfone tetra(nitrate) monohydrate is reported. The crystal structure features N—H⋯O, O—H⋯O and C—H⋯O hydrogen-bonds and π–π interactions.


Chemical context
Dapsone (4,4 0 -diaminodiphenylsulfone), a very weak Lewis base (pKa ca 2), is a drug that has been used to treat a diversity of diseases including tuberculosis, leprosy, malaria and AIDS-related pneumonia (Wilson et al., 1991). The crystal structure of dapsone was first reported in 1970 (Dickenson et al., 1970) and redetermined a number of times (Bocelli & Cantoni, 1990;Su et al., 1992;Bertolasi et al., 1993). The structure of its partial (0.33) hydrate has also been determined (Kus'mina et al., 1981;Bel'skii et al., 1983). To the best of our knowledge there are no reported polymorphic forms of dapsone.
Sulfones are good hydrogen-bond acceptors since their ability to participate as such in hydrogen-bonding interactions is increased by the highly polar nature of the sulfur-oxygen bond (Almarsson & Zaworotko, 2004;Eccles et al., 2010). In order to enrich the knowledge of such kinds of compound and to investigate the effect of hydrogen bonding on the chemical and structural features, we report here the synthesis and crystal structure analysis of a new salt of dapsone, the hydrated dinitrate 2C 12 H 14 N 2 O 2 S 2+ Á4NO 3 À ÁH 2 O. In terms of other compounds containing the ammonio-substituted dapsone cation species, only the mono-ammonio-dapsone salt 4-(4-aminophenylsulfonyl)anilinium 2-carboxy-4,6-dinitrophenolate monohydrate has been reported (Smith & Wermuth, 2013). Surprisingly, the literature has not revealed any other crystal structure containing the (4,4 0 -diammonio)substituted diphenylsulfone. ISSN 2056-9890

Figure 2
Part of the crystal structure, showing double cationic chains andassociations, with nitrate anions and the water molecule omitted.

Figure 1
The asymmetric unit of the title compound, showing the atom-numbering scheme for the two cations (A, left and B, right), the four nitrate anions and the water molecule of solvation. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii.    Hydrogen-bond interactions around each nitrate anion and aggregation of R 2

Supramolecular features
The hydrogen-bonded supramolecular assembly in the crystal of the title compound is generated by a total of 28 independent interactions, dominated by anilinium N-HÁ Á ÁO hydrogen bonds involving only nitro-O acceptors and a single water acceptor, but no sulfone O atoms are involved ( Table 1). The water molecule forms two hydrogen bonds, to sulfone O1 vi and nitro O12 vii acceptors. The two cations A and B are associated throughinteractions [ring centroid separation CgAbÁ Á ÁCgBa i = 3.693 (3) Å [symmetry code: (i) Àx + 1, y + 1 2 , Àz + 1 2 ] and form double cationic chain sub-structures that extend along the a-axis direction (Fig. 2). The water molecule O1W, which plays a dual role as both donor and acceptor in hydrogen-bonding interactions, bridges the cations via one sulfonyl group (Fig. 3) and also bridges one nitro group, giving the combination of the hydrogen-bond sequence N3-HÁ Á ÁO1W/O1W-HÁ Á ÁO1, involving a D 2 2 (5) bond motif (Fig. 3). The cations and anions are interlinked by the ammonio N-HÁ Á ÁO(nitro) hydrogen bonds through rings and finite chains involving R 2 1 (4), R 1 2 (6), R 2 2 (7) and D(3) motifs ( Fig. 4), generating a three-dimensional hydrogen-bonded network structure in which a number of C-HÁ Á ÁO(nitro) interactions are also found (Fig. 5).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The aromatic H atoms were placed at calculated positions with C-H fixed at 0.93 Å and U iso (H) = 1.2U eq (C). All N-H atoms were located by difference methods but were subsequently restrained in the refinement with N-H = 0.89 Å and U iso = 1.2U eq (N). The H atoms of the water molecule were also located in a Fourier map and were allowed to ride with a restrained O-H bond length = 0.85 (1) Å and HÁ Á ÁH = 1.39 (2) Å and U iso (H) = 1.5 U eq (O). Although not of relevance in this achiral compound, the Flack absolute structure parameter (Flack, 1983) was determined as 0.02 (9) (Flack, 1983), 4494 Friedel pairs Absolute structure parameter 0.02 (9) Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 2012), ORTEP-3 for Windows (Farrugia, 2012), Mercury (Macrae et al., 2006)  Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 2012); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: Mercury (Macrae et al., 2006) and POVRay (Persistence of Vision, 2004). Absolute structure: (Flack, 1983), 4494 Friedel pairs Absolute structure parameter: 0.02 (9) 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. 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 > 2sigma(F 2 ) is used only for calculating R-factors(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.