2,6-Bis(bromomethyl)pyridine

In the title molecule, C7H7Br2N, the C—Br vectors of the bromomethyl groups extend to opposite sides of the pyridine ring and are oriented nearly perpendicular to its plane. In the crystal, the molecules related by a c-glide-plane operation are arranged into stacks along the c axis, with centroid–centroid distances between neighboring aromatic rings of 3.778 (2) Å. A short Br⋯Br contact of 3.6025 (11) Å is observed within a pair of inversion-related molecules.

In the title molecule, C 7 H 7 Br 2 N, the C-Br vectors of the bromomethyl groups extend to opposite sides of the pyridine ring and are oriented nearly perpendicular to its plane. In the crystal, the molecules related by a c-glide-plane operation are arranged into stacks along the c axis, with centroid-centroid distances between neighboring aromatic rings of 3.778 (2) Å . A short BrÁ Á ÁBr contact of 3.6025 (11) Å is observed within a pair of inversion-related molecules.

Related literature
For the isomorphous crystal structure of 2,6-bis(chloromethyl)pyridine, see: Betz et al. (2011). For the synthesis of the title compound, see: Dioury et al. (2009 Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006) and XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: enCIFer (Allen et al., 2004) and PLATON (Spek, 2009 2,6-Bis(bromomethyl)pyridine is a well known organic compound which serves as a precursor in various organic reactions leading to formation of a large range of pyridine derivatives. Additionally, the presence of N-donor atom enables coordination of metal ions by this molecule. Due to conformational flexibility of the bromomethyl arms, the title compound has been used as a starting material for the synthesis of macrocycles (Dioury et al., 2009).
Recently, the crystal structure of the Cl analogue of the title compound -2,6-bis(chloromethyl)pyridine -has been reported and the two compounds form an isomorphous pair.
In the crystal, π-π stacking interaction between aromatic rings of molecules forming stacks along the c axis are observed. The distance between the centroids of the stacked pyridine rings is 3.778 (2) Å (symmetry code: The bromine atoms are situated at both sides of the pyridine plane and bromomethyl arms are pointing at approximately opposite directions. In the crystal, there are two different Br···Br contacts of type I. The contact longer than the sum of van der Waals radii [Br2···Br1 i 3.7051 (11) Å; symmetry code: (i) 1 + x, y, 1 + z] links the molecules into infinite chains along [1 0 1] whereas the other one [Br2···Br2 iii 3.6025 (11) Å; symmetry code: (iii) -x, -y, -z] is formed between neighbouring chains.

Experimental
The compund was obtained according to previously reported procedure from the 2,6-bis(hydroxymethyl)pyridine (Dioury et al., 2009). Crystals suitable for the X-ray diffraction study were obtained by recrystallization from diethylether at room temperature.

Refinement
The H atoms were positioned geometrically and refined using a riding model with C-H = 0.95-0.99 Å and with U iso (H) = 1.2 times U eq (C).

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > 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.