1-(3-Bromopropyl)-4-(2-pyridyl)-1H-1,2,3-triazole

In the structure of the title compound, C10H11BrN4, the plane of the substituted 1,2,3-triazole ring is tilted by 14.84 (10)° with respect to the mean plane of the pyridine ring. The pyridine and closest triazole N atoms adopt an anti arrangement which removes any lone pair–lone pair repulsions between the N atoms. This conformation is further stabilized by weak intermolecular C—H⋯N interactions. There are two molecules in the unit cell, which form a centrosymmetric head-to-tail dimer. The dimers are stabilized through π–π interactions [centroid–centroid distance = 3.733 (4) Å and mean interplanar distance = 3.806 (12) Å] between the substituted 1,2,3-triazole ring and the pyridine rings in adjacent molecules. Each dimer interacts with two neighbouring dimers above and below, forming a slipped stack of dimers through the crystal. The 3-bromopropyl chain sits over the pyridine ring of a neighbouring molecule and the triazole rings of nearby molecules are adjacent.

In the structure of the title compound, C 10 H 11 BrN 4 , the plane of the substituted 1,2,3-triazole ring is tilted by 14.84 (10) with respect to the mean plane of the pyridine ring. The pyridine and closest triazole N atoms adopt an anti arrangement which removes any lone pair-lone pair repulsions between the N atoms. This conformation is further stabilized by weak intermolecular C-HÁ Á ÁN interactions. There are two molecules in the unit cell, which form a centrosymmetric headto-tail dimer. The dimers are stabilized throughinteractions [centroid-centroid distance = 3.733 (4) Å and mean interplanar distance = 3.806 (12) Å ] between the substituted 1,2,3-triazole ring and the pyridine rings in adjacent molecules. Each dimer interacts with two neighbouring dimers above and below, forming a slipped stack of dimers through the crystal. The 3-bromopropyl chain sits over the pyridine ring of a neighbouring molecule and the triazole rings of nearby molecules are adjacent.
Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 and SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Bruno et al., 2002); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and enCIFer (Allen et al., 2004).  in the chemistry of functionalized 1,2,3-triazoles (Meldal & Tornoe, 2008). Because they are readily synthesized using the CuAAC reaction, pyridyl functionalized 1,2,3-triazoles have begun attracting significant attention in a range of areas including anion recognition (Li & Flood, 2008), stimuli responsive foldamers (Meudtner & Hecht, 2008), drug discovery (Krivopalov & Shkurko, 2005) and coordination chemistry (Li et al. 2007;Richardson et al., 2008;Schweinfurth et al., 2008;Obata et al., 2008) The molecular structure of the new triazole compound 1 is shown in Fig. 1. The molecule consists of an essentially co-planar (2-pyridyl) and 1,2,3-triazole units attached to a 3-bromopropyl chain, the plane of the substituted 1,2,3-triazole ring is tilted by 14.84 (10)° with respect to the mean plane of the pyridine ring system. As is commonly observed (Obata et al., 2008;Schweinfurth et al., 2008) N1 in the pyridine ring and N2 of the triazole ring adopt an anti arrangement which removes any lone pair-lone pair repulsions between the nitrogen atoms. Additionally, the anti conformation is stabilized by weak C-H···N interactions. There are two molecules of 1 in the unit cell which form a centrosymmetric head to tail dimer that is stabilized through a π-π interaction [centroid-centroid distance = 3.733 (4) Å, mean interplanar distance 3.806 (12) Å] between the substituted 1,2,3-triazole and the pyridine rings in adjacent molecules. In the extended crystal each dimer interacts with two neighbouring dimers above and below to form slipped stacks of dimers through the crystal. The 3-bromopropyl chain sits over the pyridine ring of the neighbouring molecule and the triazole rings of nearby molecules are adjacent [centroid-centroid distance = 4.691 (4) Å]. Unlike the dimer units, the extended stacks appear not to be stabilized by π-π interactions, the mean interplanar distance between dimers of 1 is 4.060 Å are outside the range normally expected for a π-π interaction. A steric interaction between the bromopropyl chain on one molecule of 1 and the pyridine ring on the adjacent molecule in the next dimer prevents a closer face to face interaction of the aromatic rings in the different dimer units.

Experimental
The title compound, C 10 H 11 BrN 4 (1) was obtained as a by-product during the attempted synthesis of a ditopic propyl bridged bis((2-pyridyl)-1,2,3-triazole) ligand. X-ray quality colourless crystals were obtained by slow evaporation of a petroleum ether solution of 1 but were weakly diffracting.

Refinement
All H-atoms bound to carbon were refined using a riding model with d(C-H) = 0.93 Å, U iso =1.2U eq (C) for the CH H atoms and d(C-H) = 0.97 Å, U iso = 1.2U eq (C) for CH 2 H atoms.
Figures Fig. 1. The molecular structure of compound 1, showing the atom numbering scheme. The thermal displacement ellipsoids are drawn at the 50% probability level.  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 Rfactors(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.