Crystal structure of 5-chloro-N 1-(5-phenyl-1H-pyrazol-3-yl)benzene-1,2-diamine

The title compound, crystallizes with two independent molecules (A and B) in the asymmetric unit, which are far from planar. The aryl rings are inclined to one another by 58.77 (9)° in molecule A and by 36.95 (8)° in molecule B.


Structural commentary
There are two independent molecules (A and B) in the asymmetric unit of the title compound (Ib), as illustrated in Fig. 2. They are composed of three unsaturated rings, two of which are connected by a bridging amino group. The molecules are not planar as a result of steric repulsion between the rings, which results in some disturbance of the conjugation. Thus, the presence of a shortened intramolecular contact C2 Á Á Á H11 [2.80 Å in molecule A and 2.81 Å in molecule B as ISSN 2056-9890 compared with the sum of their van der Waals radii of 2.87 Å (Zefirov, 1997)], indicates the presence of repulsion between the pyrazole ring and the phenyl substituent. The steric strain is compensated for by the elongation of the C1-C10 bond: 1.486 (2) Å in molecule A and 1.482 (2) Å in molecule B compared to a mean bond length of 1.470 Å for a typical conjugated system (Bü rgi & Dunitz, 1994). In addition, the C2-C1-C10 bond angle increases to 130.6 (2) in both molecules, and the pyrazole and phenyl rings are twisted with respect to each other, with torsion angle C2-C1-C10-C11 being 18.1 (3) in molecule A and À14.3 (3) in molecule B.
The bridging nitrogen atom, N3, has an almost planar configuration (the bond-angle sum is 356 in A and 358 in B). The N4H 2 amino group has a pyramidal configuration (bondangle sum is 329 in A and 325 in B). The C5-N4 bond, 1.422 (3) Å in A and 1.425 (3) Å in B, is elongated in comparison with the mean value of 1.394 Å ; this elongation is probably caused by the involvement of the nitrogen lone pair in hydrogen bonding (Table 1) The molecular structure of the two independent molecules (A and B) of compound (Ib), with the atom labelling. Displacement ellipsoids are drawn at the 30% probability level.
Cg3 is the centroid of the C10A-C15A ring.

Supramolecular features
In the crystal, molecules are linked by two pairs of N-HÁ Á ÁN hydrogen bonds, forming A-B dimers (Table 1 and Fig. 3). The dimers are linked by a fifth N-HÁ Á ÁN hydrogen bond to form a tetramer-like arrangement (Table 1 and Fig. 3). These stack up the a-axis direction, forming columns (Table 2 and Fig. 4), which are linked by C-HÁ Á Á interactions, forming layers parallel to the ac plane.
General procedure: Hydrazine hydrate (0.5 ml, 85% aq. solution) was added to a solution of the corresponding 4-phenyl-1,3-dihydro-2H- A view along the a axis of the crystal packing of compound (Ib). The N-HÁ Á ÁN hydrogen bonds are shown as dashed lines and the C-HÁ Á Á interactions as blue arrows (see Table 1). For clarity, only the H atoms involved in these interactions have been included.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles