1-(Benzotriazol-1-yl)-2-bromoethanone

In the title compound C8H6BrN3O, the benzotriazole ring is essentially planar (r.m.s. deviation = 0.0034 Å) and the bromoacetyl unit is twisted at a dihedral angle of 15.24 (16)° with respect to it. In the crystal, pairs of C—H⋯O hydrogen bondings result in the formation of inversion dimers, forming R 2 2(12) rings, which are connected by further C—H⋯O interactions into chains extending along the b-axis direction.

In the title compound C 8 H 6 BrN 3 O, the benzotriazole ring is essentially planar (r.m.s. deviation = 0.0034 Å ) and the bromoacetyl unit is twisted at a dihedral angle of 15.24 (16) with respect to it. In the crystal, pairs of C-HÁ Á ÁO hydrogen bondings result in the formation of inversion dimers, forming R 2 2 (12) rings, which are connected by further C-HÁ Á ÁO interactions into chains extending along the b-axis direction.

Comment
The title compound shows antitumor activity mediated by inhibition of ascites sarcoma 180 in mice (Nakagawa et al., 1973). Herein we report the crystal structure of the title compound.

Experimental
A solution of thionyl chloride (0.4 mL, 5.5 mmol) and benzotriazole (1.79 g., 15 mmol) in methylene chloride (30 mL) was stirred at 293 K for 30 minutes. Bromoacetic acid (0.7 g., 5 mmol) was then added and the heterogeneous mixture was stirred for 2 hr. The solid was filtered and methylene chloride (50 mL) was added to the filtrate. The organic layer was extracted with saturated 4N HCl (3x, 15 mL), brine (2x, 5 mL) and dried over anhydrous Na 2 SO 4 . The crystals of the title compound suitable for X-ray crystallographic analysis were obtained by slow evaporation of methylene chloride (1.0 g, 83% yield).

Refinement
The H-atoms were positioned with idealized geometry with C-H = 0.93 and 0.97 Å for aromatic and methylene Hatoms, respectively, and were refined as riding with U iso (H) = 1.2U eq (C).

Computing details
Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 1999)     where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.43 e Å −3 Δρ min = −0.51 e Å −3 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq