6-(1H-Tetrazol-5-yl)-1H-indole monohydrate

In the title compound, C9H7N5·H2O, the tetrazole ring forms a dihedral angle of 1.82 (1)° with the mean plane of the indole fragment. In the crystal, molecules are linked by intermolecular O—H⋯N, N—H⋯O and N—H⋯N hydrogen bonds into a two-dimensional network parallel to (100). Addtional stabilization is provide by weak π–π interactions with a centroid–centroid distance of 3.698 (2) Å.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5195). In recent decades, there have been some reports on the compounds which are synthesized by the combination of the tetrazole and indole rings (Itoh et al.,1995) and property studies reveals that these compounds always perform unique pharmacological activities (Semenov et al., 2002). In order to obtain such compounds, we have attempted to synthesize the indole compounds with tetrazole as a substituent. Herein, we report the crystal structure of the title compound (I). The molecular structure of (1) is shown in Fig. 1.

Experimental
All chemicals used (reagent grade) were commercially available. 6-Cyanoindole was synthesized following the methods described by Frederick (1949). To the stirring DMF solution of NaN 3 and triethylamine, 6-cyanoindole was added. Then the mixture was heated to 120, about 1 h later, the solution was cooled to room temperature, and DMF was distilled in a vacuum. With some follow-up treatment, the crude product was recrystallized in methanol solution and seven days later, yellow prism crystal was obtained.

Refinement
H atoms bound to C and N atoms were placed in calculated positions and refined using a riding model, with C-H = 0.94Å and U iso (H) =1.2U eq (C) or N-H = 0.86Å and U iso (H) =1.5U eq (N) . The H atoms of the water molecule were located in a difference map and refined freely. Fig. 1. The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as a small spheres of arbitrary radius. Fig. 2. Part of the crystal structure with hydrogen bonds and π-π interactions shown as dashed lines. Only H atoms involed in hydrogen bonds are shown. CP denotes a ring centroid. [Symmetry codes: (i) x, y-1,z; (ii) -x+1, y+1/2, -z+1/2; (iii)x, -y+1/2, z-1/2; (iv) x, -y+3/2, z-1/2] 6-(1H-Tetrazol-5-yl)-1H-indole monohydrate

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.