1,3-Benzothiazol-2-amine

In the crystal structure of the title compound, C7H6N2S, molecules related by an inversion center are linked via N—H⋯N hydrogen bonds involving the amino groups, forming dimers. In turn, these dimers are linked via a second N—H⋯N hydrogen bond, forming an infinite two-dimensional network parallel to (011).


Comment
The first reference to the crystal structure of the title compound appeared in a study by (Goubitz et al., 2001) on the crystal structure determination of a series of small organic molecules from powder diffraction data. The analysis, using Guinier photographic data, was successful but the final Reitveld refinement gave an R f value of only 16.4%. Herein, we report on a single-crystal low temperature analysis (173 K) of the title compound.
The molecular structure of the title compound is illustrated in Fig. 1. The geometric parameters are available in the archived CIF and are similar to those in the above mentioned compounds.

Experimental
Single crystals of the title compound were obtained by recrystallization from methanol of a reagent grade sample.

Refinement
All the H-atoms could be located in difference electron-density maps. The amino H-atoms were refined isotropically with distance restraints: N-H = 0.82 (2) Å. The aromatic H-atoms were included in calculated postitions and treated as riding atoms: C-H = 0.95 Å with U iso (H) = 1.2U eq (parent C-atom). Fig. 1. A view of the molecular structure of the title compound, with the displacement ellipsoids drawn at the 50% probability level.

Figures
supplementary materials sup-2 Fig. 2. A view along the a axis of the crystal packing of the title compound, illustrating the formation of the centrosymmetric hydrogen bonded dimers and the two-dimensional hydrogen bonded network (see Table 1 for details; the hydrogen bonds are shown a pale-blue dashed lines; H-atoms not involved in hydrogen bonding have been omitted for clarity).

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles 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 > σ(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.