1-(5-Bromo-2-oxoindolin-3-ylidene)thiosemicarbazone

The title molecule, C9H7BrN4OS, is essentially planar [r.m.s. deviation = 0.066 (2) Å], the maximum deviation from the mean plane through the non-H atoms being 0.190 (3) Å for the terminal amine N atom. In the crystal, molecules are linked through N—H⋯O and N—H⋯S interactions, generating infinite chains along the b-axis direction. In turn, the chains are stacked along the a axis via π–π interactions [centroid–centroid distance = 3.470 (2) Å] and further connected by N—H⋯Br interactions into a three-dimensional network. An intramolecular N—H⋯O hydrogen bond is also observed.

The title molecule, C 9 H 7 BrN 4 OS, is essentially planar [r.m.s. deviation = 0.066 (2) Å ], the maximum deviation from the mean plane through the non-H atoms being 0.190 (3) Å for the terminal amine N atom. In the crystal, molecules are linked through N-HÁ Á ÁO and N-HÁ Á ÁS interactions, generating infinite chains along the b-axis direction. In turn, the chains are stacked along the a axis viainteractions [centroid-centroid distance = 3.470 (2) Å ] and further connected by N-HÁ Á ÁBr interactions into a three-dimensional network. An intramolecular N-HÁ Á ÁO hydrogen bond is also observed.
We gratefully acknowledge financial support by the State of Schleswig-Holstein, Germany. We thank Professor Dr Wolfgang Bensch for access to his experimental facilities. We gratefully acknowledge financial support through the DECIT/ SCTIE-MS-CNPq-FAPERGS-Pronem-# 11/2029-1 and PRONEX-CNPq-FAPERGS projects. KCTB thanks FAPEAM for the award of a scholarship and ABO acknowledges financial support through the FAPITEC/SE/ FUNTEC/CNPq PPP 04/2011 program.  (Chiyanzu et al., 2003). As part of our study of thiosemicarbazone derivatives, we report herein the crystal structure of 5-bromoisatin-3-thiosemicarbazone (Campaigne & Archer, 1952). In the title compound, in which the molecular structure matches the asymmetric unit, the maximal deviation from the least squares plane through all non-hydrogen atoms amount to 0.1896 (32) Å for N4.The molecule shows an E conformation for the atoms about the N2-N3 bond (Fig. 1). The E conformation for the thiosemicarbazone fragment is also observed in the crystal structure of the 5-bromoisatin-3-thiosemicarbazone acetonitrile monosolvate (Pederzolli et al., 2011) and is related with the intramolecular N-H···O Hinteraction (Table 1). The mean deviations from the least squares planes for the C1-C8/Br1/N1 and C9/N2-N4/S1 fragments amount to 0.0568 (26) Å for O1 and 0.0394 (27) Å for N3, respectively, and the dihedral angle between the two planes is 9.01 (12)°. The molecules are connected via centrosymmetric pairs of N-H···S and N-H···O interactions and additionally by N-H···Br interactions ( Fig. 2 and Table 1) forming a three-dimensional hydrogen-bonded network, which stabilizes the crystal packing. Additionally, π-π-interactions are observed, with C···C distances = 3.396 (6) Å. The molecules are arranged in layers and are stacked into the crystallographic a-axis direction (Fig. 3).

Experimental
Starting materials were commercially available and were used without further purification. The 5-bromoisatine-3-thiosemicarbazone synthesis was adapted from a procedure reported previously (Campaigne & Archer, 1952). A mixture of of 5-bromoisatin (8,83 mmol) and thiosemicarbazide (8,83 mmol) in ethanol (50 ml) in the presence of a catalytic amount of hydrochloric acid was refluxed for 6 h. After cooling and filtering, the title compound was obtained. Crystals suitable for X-ray diffraction of 5-bromoisatine-3-thiosemicarbazone were obtained unexpectedly from an unsuccessful reaction of SnCl 2 dihydrate with the title compound in methanol and dichloromethane by the slow evaporation of the solvents.

Refinement
All non-hydrogen atoms were refined anisotropically. All C-H and N-H atoms were located in difference map but were positioned with idealized geometry and refined isotropically with U iso (H) = 1.2 U eq (C) using a riding model with C -H = 0.93 Å for aromatic and N-H = 0.86 Å for methyl H atoms. The terminal N-H atoms were located in difference map, their bond lengths were set to 0.86 Å and afterwards they were refined isotropically with U iso (H) = 1.5 U eq (N) using a riding model. (Stoe & Cie, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 40% probability level.

1-(5-Bromo-2-oxoindolin-3-ylidene)thiosemicarbazone
Crystal data C 9 H 7 BrN 4 OS M r = 299.16 Orthorhombic, P2 1 2 1 2 1 Hall symbol: P 2ac 2ab a = 4.0185 (2)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.73 e Å −3 Δρ min = −0.55 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0123 (16) Absolute structure: Flack (1983), 951 Friedel pairs Flack parameter: −0.015 (13) 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 > σ(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.