N-(2-Allyl-4-chloro-2H-indazol-5-yl)-4-methoxybenzenesulfonamide hemihydrate

The fused five- and six-membered rings in the title compound, C17H16ClN3O3S·0.5H2O, are practically coplanar, with the maximum deviation from the mean plane being 0.057 (3) Å for the C atom bound to the exocyclic N atom. The indazole system makes a dihedral angle of 66.18 (12)° with the plane through the benzene ring, and it is nearly perpendicular to the allyl group, as indicated by the N—N—C—C torsion angle of 79.2 (3)°. In the crystal, the water molecule, lying on a twofold axis, forms O—H⋯N and accepts N—H⋯O hydrogen bonds. Additional C—H⋯O hydrogen bonds contribute to the formation of a chain along the b-axis direction.

The fused five-and six-membered rings in the title compound, C 17 H 16 ClN 3 O 3 SÁ0.5H 2 O, are practically coplanar, with the maximum deviation from the mean plane being 0.057 (3) Å for the C atom bound to the exocyclic N atom. The indazole system makes a dihedral angle of 66.18 (12) with the plane through the benzene ring, and it is nearly perpendicular to the allyl group, as indicated by the N-N-C-C torsion angle of 79.2 (3) . In the crystal, the water molecule, lying on a twofold axis, forms O-HÁ Á ÁN and accepts N-HÁ Á ÁO hydrogen bonds. Additional C-HÁ Á ÁO hydrogen bonds contribute to the formation of a chain along the b-axis direction.   Table 1 Hydrogen-bond geometry (Å , ). supplementary materials Acta Cryst. (2013). E69, o1353 [doi:10.1107/S1600536813020606]
The cohesion of the crystal structure is ensured by O4-H4···N2, N1-H1···O4 and C7-H7···O3 hydrogen bonds formed between the water and the organic molecules forming a one-dimensional chain along the b axis (Table 2).

Experimental
A mixture of 2-allyl-5-nitroindazole (1.22 mmol) and anhydrous SnCl 2 (1.1 g, 6.1 mmol) in absolute ethanol (25 ml) was heated at 333 K for 6 h. After reduction, the starting material disappeared, and the solution was allowed to cool down.
The pH was made slightly basic (pH 7-8) by addition of 5% aqueous potassium bicarbonate before extraction with ethyl acetate. The organic phase was washed with brine and dried over magnesium sulfate. The solvent was removed to afford the amine, which was immediately dissolved in pyridine (5 ml) and then reacted with 4-methoxybenzenesulfonyl chloride (1.25 mmol) at room temperature for 24 h. After the reaction mixture was concentrated in vacuo, the resulting residue was purified by flash chromatography (eluted with ethyl acetate:hexane 1:9). The title compound was recrystallized from its ethanol solution.

Refinement
The C-bound H atoms were located in a difference map and treated as riding with C-H = 0.93-0.97 Å for methyl-, methylene-, aromatic-H, respectively. The N-H and O-H atoms were included in their "as located" positions. U iso (H) = 1.2U eq (aromatic, methylene, NH and OH) and U iso (H) = 1.5 U eq (methyl).

Figure 1
Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.34 e Å −3 Δρ min = −0.33 e Å −3 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.