[1-Phenyl-2-(4-pyridyl)ethylidene]hydrazine

The title compound, C13H13N3, is non-planar, with the pyridine and phenyl rings inclined at an angle of 80.7 (3)°. The central ethylidenehydrazine atoms lie in a plane [mean deviation = 0.013 (1) Å], which forms dihedral angles of 88.5 (1) and 9.4 (1)° with the pyridine and phenyl rings, respectively. In the crystal structure, molecules are linked by intermolecular N—H⋯N hydrogen bonds into infinite chains propagating along the b axis.

The title compound, C 13 H 13 N 3 , is non-planar, with the pyridine and phenyl rings inclined at an angle of 80.7 (3) . The central ethylidenehydrazine atoms lie in a plane [mean deviation = 0.013 (1) Å ], which forms dihedral angles of 88.5 (1) and 9.4 (1) with the pyridine and phenyl rings, respectively. In the crystal structure, molecules are linked by intermolecular N-HÁ Á ÁN hydrogen bonds into infinite chains propagating along the b axis.
The author thanks Hengyang Normal University for supporting this study.

Comment
The chemical properties of hydrazine derivatives with various substitution patterns have been investigated extensively, because of their ability to bind to transition metal ions or to form unusual organic helical chains through intermolecular hydrogen bonds (De et al., 2006;Patra & Goldberg, 2003). A new hydrazine derivative has been synthesized and its crystal structure is reported here, Fig. 1.
The whole molecule is nonplanar with a dihedral angle of 80.7 (3)° between the pyridine and phenyl ring. However, the central C6/C7/N2/N3 motifs are planar with the mean deviation from the plane of 0.013 (1) Å, which also generates dihedral angles of 88.5 (1)° and 9.4 (1)° with the pyridine and phenyl rings, respectively. The N2 atom forms an intramolecular C-H···N hydrogen bond with phenyl ring H13 atoms.
The crystal packing (Fig. 2) shows the amino group acts as a donor to form an intermolecular N-H···N hydrogen bond towards pyridine N atom forming infinite chains parallel to the b axis.

Experimental
Benzoyl chloride (4.85 g, 34.5 mmol) was added to a solution of 4-methylpyridine (4.14 g, 44.5 mmol) in chloroform (20 ml) over 1 h at room temperature. The resulting solution was stirred for 5 h and the solvent was evaporated under vacuum to give an orange precipitate, which were triturated with toluene (20 ml) to obtain an orange solution. Then hydrazine hydrate (4 ml, 80%, 66 mmol) was added to this solution and stirred for 10 h. The solvent was removed under reduced pressure and the residue was recrystallized from dichloromethane to give light-yellow prism-like crystals of the title compound. Yield: 0.82 g (11%).

Refinement
The carbon-bound H atoms were placed at calculated positions (C-H = 0.93 Å or 0.97 Å) and refined as riding, with U(H) = 1.2U eq (C). The amine H atoms were located in a difference Fourier map and allowed to ride on the N atom with N-H = 0.86 Å, U iso = 1.2U eq (N). In the absence of significant anomalous dispersion effects, Freidel pairs were merged. Fig. 1. The title molecule with displacement ellipsoids drawn at the 30% probability level, and H atoms as spheres of arbitrary radius.

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.