12-(4-Methoxyphenyl)-10-phenyl-3,4,5,6,8,10-hexaazatricyclo[7.3.0.02,6]dodeca-1(9),2,4,7,11-pentaene

In the title compound, C19H14N6O, the fused 12-membered tetrazolo/pyrimidine/pyrrole ring system is almost planar (r.m.s. deviation = 0.013 Å). The 4-methoxyphenyl and phenyl substituents on the pyrrole ring are both twisted with respect to the fused-ring system [dihedral angles = 25.39 (18) and 36.42 (18)°, respectively]. Intramolecular C—H⋯N interactions occur. In the crystal, molecules pack into layers in the ac plane and these are connected along the b axis via C—H⋯π and π–π [centroid–centroid separation = 3.608 (3) Å] interactions.


Comment
Interest in fused tetrazolopyrimidines relates, in part, to their biological activities (Shishoo & Jain, 1992;Desai & Shah, 2006). In continuation of complementary structural studies (Jotani et al. 2010a;Jotani et al. 2010b;Shah et al. 2010), the synthesis and X-ray crystal structure determination of the title compound, (I), are reported herein.
In the crystal packing, the molecules pack into layers parallel to (0 1 0) with connections between the layers provided by C-H···π, Table 1, and π-π interactions between the five-membered tetrazolo and pyrrole rings The Semi-empirical Quantum Chemical Calculations were performed on the experimental structure using the MO-PAC2009 programme (Stewart, 2009) to optimize the structure with the Parametrization Model 6 (PM6) approximation together with the restricted Hartree-Fock closed-shell wavefunction; minimizations were terminated at an r.m.s. gradient of less than 0.01 kJ mol -1 Å -1 . The most significant difference between the experimental and calculated structures is found in the relative orientation of the 4-methoxyphenyl ring with respect to the pyrrol ring to which it is bonded. This is quantified in the C3-C6-C7-C8 torsion angle of 38.9 ° cf. 24.2 (9) ° in the experimental structure. The orientation of the pyrrole-benzene ring remains unaffected.as seen in the (torsion angles is C4-N6-C14-C15 torsion angle of -38.8 ° cf. -39.1 (7) ° (experiment).

Experimental
To a well stirred mixture of 5-(4-methoxyphenyl)-7-phenyl-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 conditions for 1.5 h. Thereafter, the two phases were separated. The aqueous phase was extracted with toluene and the combined organic layers were washed with water. The excess solvent was distilled off under reduced pressure. The obtained solid was dried to yield (I) which was crystallized from dioxane to obtain the final product (70 % yield, m.pt. 489-491 K).
The crystals used for X-ray crystallography were obtained by slow evaporation from the an ethanol solution of (I).
supplementary materials sup-2 Refinement The C-bound H atoms were geometrically placed (C-H = 0.93-0.96 Å) and refined as riding with U iso (H) = 1.2-1.5U eq (parent atom). In the absence of significant anomalous scattering effects, 1378 Friedel pairs were averaged in the final refinement. Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 35% probability level. 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 > 2σ(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.