tert-Butyl(2-hydroxyethyl)azanium 4-[(1,3-thiazol-2-ylazanidyl)sulfonyl]aniline

Two pairs of independent cations and anions comprise the asymmetric unit of the title salt, C6H16NO+·C9H8N3O2S2 −. The cations are virtually superimposable and each exhibits a gauche disposition of the hydroxy O and ammonium N atoms [the O—C—C—N torsion angles are 55.5 (3) and 57.5 (3)°]. Significant differences are seen in the molecular structures of the anions as seen in the S—N—C—S [1.1 (3) and 32.9 (3)°] and C—S—N—C [−69.7 (2) and 91.4 (2)°] torsion angles. Despite the variations in conformation, intramolecular hypervalent S⋯O interactions persist in each anion [3.078 (2) and 2.8730 (19) Å]. In the crystal, supramolecular double layers are formed in the bc plane, being sustained by O—H⋯N, N—H⋯O and N—H⋯N hydrogen bonding. These are connected along the a axis via C—H⋯O interactions.

Two independent cations, Figs 1 and 2, and two independent anions, Figs 3 and 4, comprise the asymmetric unit of (I).
As expected from the composition, significant hydrogen bonding is apparent in the crystal structure of (I). Thus, O-H···N, N-H···O and N-H···N interactions lead to supramolecular double layers in the bc plane, Fig. 6 and Table 1. Both of the independent hydroxyl groups hydrogen bonds to a single anion, i.e. O21-H to the thiazole-N1, and O31-H to the azanide-N2. The ammonium cations are connected to each other via N-H···O(hydroxyl) hydrogen bonds with the remaining ammonium-H atom on each cation connected to the same anion, via N21-H···N12-azanide and N31-H···N11(thiazole) hydrogen bonds. This results in the formation of two cation plus two anion aggregates. These are connected into a two dimensional sheet via aniline-N-H···O(sulfonyl) hydrogen bonds. The sheet thus formed is connected into a double layer via aniline-N31-H···O2(sulfonyl) hydrogen bonds, indicated by ′(x)′ in Fig. 6, leading to 12-membered {···HNH···O═S═O···} 2 synthons. The N3-H1n atom, labelled with ′(y)′ in Fig. 6, does not participate in a formal hydrogen bond. The closest potential acceptor atom, i.e. a symmetry-related O21(hydroxyl), is proximate at 3.472 (3) Å but, the intervention of a methyl group precludes the formation of a significant hydrogen bonding interaction.
In addition to C-H···O interactions that contribute to the stability of the double layer, further C2-H···O11 contacts occur between layers that stack along the a direction, Fig. 7.

Experimental
Sulfathiazole (Sigma-Aldrich) and tert-butyl(2-hydroxyethyl)amine (Sigma-Aldrich) were used as delivered. Single crystals of (I) were harvested from a 1:1 methanol/tetrahydrofuran (10 ml) solution of the amine and a stoichiometric   Molecular structure of the second independent cation of (I) showing atom-labelling scheme and displacement ellipsoids at the 50% probability level.

Figure 3
Molecular structure of the first independent anion of (I) showing atom-labelling scheme and displacement ellipsoids at the 50% probability level.  Molecular structure of the second independent anion of (I) showing atom-labelling scheme and displacement ellipsoids at the 50% probability level.   Unit-cell contents in (I) viewed in projection down the b axis. One double-layer is presented in space-filling mode.

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 cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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.