4-[5-Amino-4-(4-fluorophenyl)-3-(pyridin-4-yl)-1H-pyrazol-1-yl]benzonitrile

In the crystal structure of the title compound, C21H14FN5, the pyrazole ring forms dihedral angles of 38.0 (1), 40.0 (1) and 28.5 (1)° with the directly attached 4-fluorophenyl, pyridine and benzonitrile rings, respectively. The crystal packing is characterized by N—H⋯N hydrogen bonds, which result in a two-dimensional network parallel to the ac-plane.

In the crystal structure of the title compound, C 21 H 14 FN 5 , the pyrazole ring forms dihedral angles of 38.0 (1), 40.0 (1) and 28.5 (1) with the directly attached 4-fluorophenyl, pyridine and benzonitrile rings, respectively. The crystal packing is characterized by N-HÁ Á ÁN hydrogen bonds, which result in a two-dimensional network parallel to the ac-plane.
The crystal packing (Fig. 2) shows that the amino function acts as a hydrogen bond donor of two intermolecular hydrogen bonds formed to two different molecules -one to the nitrogen atom (N26) of the pyridine ring and one to the nitrogen atom (N14) of the nitrile group. The length of the hydrogen bonds is 2.14Å and 2.58 Å, respectively ( Table 1).
The two hydrogen bonds result in a two dimensional network parallel to the ac-plane.
Experimental 20 mmol of LDA were added to 30 ml of dry THF in a three neck flask and cooled to 194 K. 14 mmol of 4-fluorophenylacetonitril in 10 ml THF were added dropwise and the reaction mixture was stirred for 45 min. 5 mmol of N-(4-cyanophenyl)-4-pyridinecarbohydrazonoyl chloride were added slowly and stirring of the reaction mixture was continued for 1 h. After warming to 293 K, 50 ml of water were added to the reaction mixture which then was extracted with ethyl acetate (2x 50 mL). The combined organic layers were dried over Na 2 SO 4 . The organic solution was concentrated to about 5 ml and the product precipitated as pure pale brown crystalls which were washed with diethyl ether. Yield 62%.

Refinement
Hydrogen atoms attached to carbons were placed at calculated positions with C-H = 0.95 Å (aromatic) or 0.98-0.99 Å (sp 3 C-atom). All H atoms were refined in the riding-model approximation with isotropic displacement parameters (set at 1.2-1.5 times of the U eq of the parent atom).

Computing details
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software (Enraf-Nonius, 1989 (18) 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.