4-(1,2,4-Triazol-1-yl)aniline

In the title compound, C8H8N4, the dihedral angle between the triazole ring [maximum deviation = 0.003 (1) Å] and the benzene ring is 34.57 (7)°. In the crystal, molecules are linked into sheets lying parallel to the ac plane via intermolecular N—H⋯N and C—H⋯N hydrogen bonds. Aromatic π–π [centroid–centroid distance = 3.6750 (8) Å] stacking and N—H⋯π interactions are also observed.


D-HÁ
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009). HKF and CKQ thank Universiti Sains Malaysia (USM) for the Research University Grant (No. 1001/PFIZIK/811160). CKQ also thanks USM for the award of a USM fellowship. AMI is thankful to the Director of the National Institute of Technology for providing research facilities and also thanks the Board for Research in Nuclear Sciences, Department of Atomic Energy, Government of India, for a Young Scientist Award.

Comment
Compounds incorporating heterocyclic ring systems continue to attract considerable interests due to the wide range of biological activities they possess (Isloor et al., 2000). Triazoles are a class of heterocyclic compounds having a five-membered ring of two carbon atoms and three nitrogen atoms (Soliman et al., 2001). They have wide range of applications. In last few decades, triazoles have received much significant attention in the field of medicinal chemistry because of their diversified biological properties like antibacterial ) and antifungal (Holla et al., 2000) activities. In recent years, 1,2,4-triazole derivatives have been found to associate with anticancer properties (Sunil et al., 2009). It is also observed that incorporation of aryl constituent into the triazoles ring systems augments the biological activities considerably.
Experimental 1,2,4-Triazole (2 g, 0.02 mol) was added lot-wise to a suspension of sodium hydride (60%, 1.47 g, 0.0308 mol) in dry DMF (20 ml) at 0°C. After the addition, the reaction mixture was stirred at the same temperature for 30 min. A solution of 4-fluoro nitrobenzene (2.82 g, 0.02 mol) in dry DMF (20 ml) was then added and the reaction mixture was stirred at room temperature for 18 h. The reaction mixture was then quenched with ice water and extracted with ethyl acetate. The organic layer was concentrated to afford a yellow solid as a nitro compound intermediate (3 g). This nitro compound was taken in methanol (30 ml) and hydrogenated using 10% palladium on carbon (0.2 g) at 3-kg pressure of hydrogen. After the reaction was over, the catalyst was filtered, the filtrate was concentrated to afford the title compound as a yellow solid. Yellow blocks were recrystallised from ethanol. Yield : 2.8g, 60 %. M.p. 433-435K.

Refinement
H1N4 and H2N4 were located in a difference Fourier map and allowed to refined freely. The remaining H atoms were positioned geometrically and refined using a riding model with C-H = 0.93 Å and U iso (H) = 1.2 U eq (C). The highest residual electron density peak is located at 0.67 Å from C3 and the deepest hole is located at 1.27 Å from C8. Fig. 1. The molecular structure of the title compound showing 50% probability displacement ellipsoids for non-H atoms.

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.