7-(4-Methoxy-phen-yl)-5-methyl-9-phenyl-7H-pyrrolo[2',3':4,5]pyrimido[1,6-d]tetrazole.

The title compound, C(20)H(16)N(6)O, is composed of a tetra-zolo ring and a 4-methoxy-phenyl and a benzene-substituted pyrrole ring at the 7 and 9 positions fused to a pyrimidine ring in a nearly planar fashion [maximum deviation of 0.018 (1) Å for the fused ring system]. A methyl group at the 5 position is also in the plane of the hetero cyclic system. The dihedral angle between the mean planes of the benzene and 4-methoxy-phenyl rings is 40.4 (2)°. The dihedral angles between the mean planes of the pyrimidine and the benzene and 4-methoxy-phenyl rings are 15.6 (5)° and 52.6 (7)°, respectively. A weak intra-molecular C-H⋯N hydrogen bond inter-action, which forms an S(7) graph-set motif, helps to establish the relative conformations of the tetrazolo and benzene rings. In the crystal, weak inter-molecular C-H⋯O, C-H⋯π and π-π stacking inter-actions [centroid-centroid distances = 3.5270 (16), 3.5113 (16), 3.7275 (17) and 3.7866 (17) Å] link the mol-ecules into a two-dimensional array obliquely parallel to (101) and propagating along the b axis.

The title compound, C 20 H 16 N 6 O, is composed of a tetrazolo ring and a 4-methoxyphenyl and a benzene-substituted pyrrole ring at the 7 and 9 positions fused to a pyrimidine ring in a nearly planar fashion [maximum deviation of 0.018 (1) Å for the fused ring system]. A methyl group at the 5 position is also in the plane of the hetero cyclic system. The dihedral angle between the mean planes of the benzene and 4-methoxyphenyl rings is 40.4 (2) . The dihedral angles between the mean planes of the pyrimidine and the benzene and 4-methoxyphenyl rings are 15.6 (5) and 52.6 (7) , respectively. A weak intramolecular C-HÁ Á ÁN hydrogen bond interaction, which forms an S(7) graph-set motif, helps to establish the relative conformations of the tetrazolo and benzene rings. In the crystal, weak intermolecular C-HÁ Á ÁO, C-HÁ Á Á andstacking interactions [centroid-centroid distances = 3.5270 (16), 3.5113 (16), 3.7275 (17) and 3.7866 (17) Å ] link the molecules into a two-dimensional array obliquely parallel to (101) and propagating along the b axis.

S1. Comment
Fused tetrazolopyrimidines are important to the activities of a variety of biological substances (Willkinson, 1992;Omer et al., 1991;Schram et al., 1975). Moreover, fused pyrimidines having a halogen at the 2-or 4-position seem to be more labile towards a nucleophilic substitution reaction with reagents such as piperadine, piperazine, morpholine, hydrazine and azides to form potent bi and triheterocycles (Dave & Shah, 2002;Peinador et al., 1992;Schneller & Clough, 1992;Shishoo & Jain, 1992). The reduction of tetrazolopyrimidines via azidolysis studies have been shown to be to attractive to development of synthetically important 4-aminopyrimidines (Shishoo & Jain, 1992;Hand & Backer, 1984). The treatment of sodium azide with 4-chloropyrrolo[2,3-e] pyrimidine can result the formation of either an azido group or tetrazole ring upon a fused pyrimidine ring. Such nucleophilic substitution reactions have rarely been attempted in pyrrolo[2,3-e] pyrimidines (Dave & Shah, 2002;Ali & Swealan, 1992). In view of the importance of these molecules, a crystal structure of the title compound, C 20 H 16 N 6 O, (I) has been determined.
The title compound, C 20 H 16 N 6 O, (I), is composed of a tetrazolo ring and a 4-methoxyphenyl and benzene substituted pyrrole ring at the 7 and 9 position fused to a pyrimidine ring in a nearly planar fashion (Fig. 1). The r.m.s.deviation of atoms of the fused ring from the mean plane through the heterotricyclic system is 0.0085 Å, with a maximum deviation of -0.018 (1) and 0.013 (1) Å for atoms C2 and C3 respectively. Bond lengths and angles for the fused pyrrole and tetrazole rings in (I) are normal and similar to that observed for a related structure. The dihedral angles between the mean planes of fused pyrimidine and tetrazole rings with that of the pyrrole ring are 1.26 (6) ° and 1.13 (7)°, respectively. A methyl group at the 5 position is also in the plane of the pyrimidine ring. The dihedral angle between the mean planes of the benzene and 4-methoxyphenyl rings is 40.4 (2)°. The angles between the mean planes of the pyrimidine and the benzene and 4-methoxyphenyl rings are 15.6 (5)° and 52.6 (7)°, respectively. A weak intramolecular C13-H13···N6 hydrogen bond interaction, which forms an S(7) graph set, helps stabilize the separation angle between the tetrazolo and benzene rings. Weak intermolecular C12-H12···O1 (Fig. 2), C-H···π-ring (C7-H7B(H7C)···Cg4 [= 3.620 (2) (3.554 (2) where Cg4 = C8-C13 ring centroid; Table 1] and π-π [Cg1···Cg2; = 3.5270 (16) Fig. 3) help to link the molecules into a 2-D array obliquely parallel to (101) and propagating along the b axis.

S3. Refinement
All of the H atoms were placed in their calculated positions and then refined using the riding model with C-H = 0.95-0.98 Å, and with U iso (H) = 1.18-1.50U eq (C).

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.