7-(4-Chlorophenyl)-9-phenyl-7H-pyrrolo[3,2-e]tetrazolo[1,5-c]pyrimidine

In the title compound, C18H11ClN6, the pyrrole, pyrimidine and tetrazole rings form a nearly planar fused trihetrocyclic system with an r.m.s. deviation of 0.0387 (13) Å, to which the 4-chlorophenyl group and the phenyl group are substituted at the 7 and 9 positions, respectively. The dihedral angles between the pyrrole ring and the 4-chlorophenyl and phenyl rings are 32.1 (4) and 7.87 (7)°, respectively. In the crystal, weak intermolecular C—H⋯N and C—H⋯Cl hydrogen bonds link the molecules into a layer parallel to the (001) plane. The layers are further connected by π–π stacking interactions [centroid–centroid distances: 3.8413 (8) and 3.5352 (8) Å]. Intramolecular C—H⋯N hydrogen bonds are also present.

In the title compound, C 18 H 11 ClN 6 , the pyrrole, pyrimidine and tetrazole rings form a nearly planar fused trihetrocyclic system with an r.m.s. deviation of 0.0387 (13) Å , to which the 4-chlorophenyl group and the phenyl group are substituted at the 7 and 9 positions, respectively. The dihedral angles between the pyrrole ring and the 4-chlorophenyl and phenyl rings are 32.1 (4) and 7.87 (7) , respectively. In the crystal, weak intermolecular C-HÁ Á ÁN and C-HÁ Á ÁCl hydrogen bonds link the molecules into a layer parallel to the (001) plane. The layers are further connected bystacking interactions [centroid-centroid distances: 3.8413 (8) and 3.5352 (8) Å ]. Intramolecular C-HÁ Á ÁN hydrogen bonds are also present.
The title compound, C 18 H 11 ClN 6 , (I), is composed of a triheterocycle ring system resulting from the fusion of a benzene and 4-chlorobenzene substituted pyrrole and a tetrazole ring to a pyrimidine ring in a nearly planar fashion (Fig. 1). The r. m. s. deviation of atoms of the fused triheterocycle ring system from the mean plane through it is 0.0387 Å. The bond lengths and angles of fused tetrazole and pyrrole ring in (I) are normal and similar to those observed in a similar structure (Jotani et al., 2010). The planarity of each of the five rings (tetrazole, pyrrole, pyrimidine, 4-chlorophenyl and benzene) is confirmed by the r.m.s. deviation values (0.0017, 0.0043, 0.0107,0.0059 and 0.0017 Å), respectively. The dihedral angle between the least squares planes of the tetrazole and pyrimidine rings fused with the pyrrole ring are 2.61 (7) and 5.42 (8)°.
The dihedral angles between the mean planes of the ortho-substituted 4-chlorophenyl and benzene rings with the pyrrole ring are 32.1 (4) and 7.87 (7)°, respectively.

Experimental
The title compound is synthesized by three different routes and Phase Transfer Catalysis is novel among them. To a well stirred mixture of 5-phenyl-7-(4-chlorophenyl)-4-chloro-7H-pyrrolo[2,3-d]pyrimidine (5 mmol) and Aliquat 336 (0.5 mmol) in toluene (25 ml) was added sodium azide (6 mmol) in water (5 ml). The reaction mixture was stirred under reflux condition for 1-1.5 h. Thereafter, the two phases were separated. The aqueous phase was extracted with toluene and combined organic layers were washed with water. The excess of solvent was distilled under reduced pressure. The obtained solid was filtered, dried, and crystallized from 1,4-dioxane.

Refinement
H atoms were placed in idealized positions (C-H = 0.93-0.98 Å) and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of (I), showing the atom labelling scheme and 50% probability displacement ellipsoids. The dashed line represents a weak intramolecular C-H···N hydrogen bond.    give the title compound which was crystallized from dioxane.

Figures
(B) To a mixture of 5-phencyl-7-(4-chlorophenyl)-4-hydrazino-7H-pyrrolo[2,3-d]\ pyrimidine (0.01 mole) in acetic acid (40 ml) was added aqueous solution of sodium nitrite (20% w/v, 4.2 ml) in portions with stirring at 273-278 K and the reaction mixture was further stirred for 2 hr at the same temperature. Then it was diluted with cold water and the solid obtained was filtered, washed with water, sodium bicarbonate (20% w/v), followed by water, dried and crystallized from dioxane.
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 Rfactors(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.