6-Bromopyridine-2-carbaldehyde phenylhydrazone

The title compound, C12H10BrN3, is essentially planar (r.m.s. deviation of all non-H atoms = 0.0174 Å), with a dihedral angle of 0.5 (2)° between the two aromatic rings. In the crystal, molecules are linked by weak N—H⋯N interactions, forming a zigzag chain running parallel to [001].

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 1999 The design of molecular dynamic systems that operate by external stimuli without producing chemical waste is one of the questions of great interest in the nanotechnology field (Hirose, 2010), since these molecular systems are molecules that can exhibit structural (configurational) and chemical (constitutional) changes by the modification of external factors (presence of other molecules or metal ions, heat and/or light). Among the compounds that have attracted interest in this regard are the hydrazones which contain the imine group (-C=N-) (Kay et al., 2007). This group can undergo reversible configurational changes induced by UV light and heat (Chaur et al., 2011). For hydrazones prepared from pyridinecarboxaldehydes and pyridine or phenyl hydrazines the E/Z photoisomerization is favored by an intermolecular hydrogen bond between the hydrazine and the nitrogen of the pyridinecarboxaldehyde group resulting in a metastable state which can be returned to its original state by heating in solution (Chaur et al., 2011;Lehn, 2006;Dugave & Demange, 2003).
Besides, these compounds can exhibit dynamic properties since they can undergo coordination with suitable metals and the reversibility of the imine group gives them other features that can be used in the development of molecular machines or in the storage of information (Chaur et al., 2011). The compound reported in this paper is part of a series of compounds that are currently being prepared in our group and that exhibit dynamic properties such as photoisomerization, constitutional changes and metal coordination in order to build supramolecular systems of multiple dynamics. Herein we report the synthesis and crystal structure of 6-bromo-pyridinecarbaldehyde phenylhydrazone (I), In the molecular structure of (I), the bromopyridyl ring is planar (r.m.s. deviation of all non-hydrogen atoms = 0.0020 Å) like the central bridge (C5/C7/N2/N1/C8) (r.m.s. deviation of all non-hydrogen atoms = 0.005 Å) with a dihedral angle of 0.6 (2)° between these two planes. The central bridge forms a dihedral angle of 0.8 (2)° with the benzene ring and the bromopyridyl and benzene rings form a dihedral angle of 0.5 (2)°. The bond lengths agree with the literature values (Allen et al., 1987) and are comparable with the related structures (Yu et al., 2005;Fun et al., 2012). In the crystal packing (Fig. 2), the molecules are linked by weak N-H···N interactions (Table 1). Indeed, in this substructure, atom N1 in the molecule at (x,y,z) links to N3 atom in the molecule at (-x+2,+y-1/2,-z+1/2). The propagation of this interaction forms C(6) (Etter, 1990), continuous one-dimensional zigzag chain running parallel to [001].

Refinement
All H-atoms were positioned geometrically using riding model with [C-H = 0.93 Å with U iso (H) = 1.2U eq (C)].

Figure 3
Synthesis of the 6-bromo-pyridinecarbaldehyde phenylhydrazone where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.44 e Å −3 Δρ min = −0.72 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 > 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.

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