6-Bromopyridine-2-carboxamide

In the the title compound, C6H5BrN2O, an intramolecular N—H⋯N hydrogen bond generates an S(5) ring. In the crystal structure, intermolecular bifurcated N—H⋯(O,O) hydrogen bonds link the molecules, leading to sheets propagating in (100).

In the the title compound, C 6 H 5 BrN 2 O, an intramolecular N-HÁ Á ÁN hydrogen bond generates an S(5) ring. In the crystal structure, intermolecular bifurcated N-HÁ Á Á(O,O) hydrogen bonds link the molecules, leading to sheets propagating in (100).

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For medicinal background to inhibitors of the crysteine protease cathepsin K, see: Altmann & Aichholz (2007).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB5211).

S1. Experimental
A mixture of 30 g of 6-bromopyridine-2-carboxylic acid (0.1485 mol) in 300 ml of thionyl chloide was refluxed for twenty hours. Excess thionyl chloride was removed in vacuo. The residue was added as a slurry in dioxane or benene to 75 ml cold, stirred concentrated ammonium hydroxide. The mixture was stored overnight and the filtered to give 25 g of the title compound (yield 83.4%, m.p. 417 K). Colourless blocks of (I) were obtained by the slow evaporation of an ethyl acetate solution.

Figure 1
The molecular structure of (I) showing 50% displacement ellipsoids.  A partial packing diagram of (I). Hydrogen bonds are shown as dashed lines.

6-Bromopyridine-2-carboxamide
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.45 e Å −3 Δρ min = −0.57 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.