6-Isopropyl-3-phenyl-5-(p-tolyloxy)-3H-1,2,3-triazolo[4,5-d]pyrimidin-7(6H)-one: whole-molecule disorder

The title compound, C20H19N5O2, exhibits whole-molecule disorder the refined ratios of the two components being 0.57 (2):0.43 (2). In the major component, the essentially planar [maximum deviation 0.033 (17) Å] fused pyrimidine and triazole ring system forms a dihedral angle of 10.5 (3)° with the phenyl ring, while in the minor component of disorder this angle is 27.5 (5)°. The crystal structure is stabilized by π–π stacking interactions between symmetry-related triazole and pyrimidine rings, with centroid–centroid distances of 3.594 (10) Å.

The title compound, C 20 H 19 N 5 O 2 , exhibits whole-molecule disorder the refined ratios of the two components being 0.57 (2):0.43 (2). In the major component, the essentially planar [maximum deviation 0.033 (17) Å ] fused pyrimidine and triazole ring system forms a dihedral angle of 10.5 (3) with the phenyl ring, while in the minor component of disorder this angle is 27.5 (5) . The crystal structure is stabilized bystacking interactions between symmetry-related triazole and pyrimidine rings, with centroid-centroid distances of 3.594 (10) Å .
In recent years, we have been engaged in the preparation of the derivatives of 8-azaguanine via aza-Wittig reaction of beta-ethoxycarbonyl iminophosphorane with aromatic isocyanate (Zhao, Xie et al., 2005). As a continuation of our research for new biologically active heterocycles, the title compound, (I), was obtained from beta-ethoxycarbonyl iminophosphorane and alphalic isocyanate, and the crystal structure is reported herein.
There are no inter-or intra-molecular hydrogen bonding interactions. The molecular conformation and crystal packing are stabilized by π-π stacking interactions occurring between symmetry realted triazole and pyrimidine rings, with centroid-to-centroid distances of 3.594 (10) Å.

S2. Experimental
To a solution of carbodiimide in CH 2 Cl 2 /CH 3 CN (1:4 v/v, 15 ml) prepared according to the literature method , was added p-cresol (3 mmol) and excess K 2 CO 3 . After the reaction mixture was stirred for 12 h. The solvent was removed under reduced pressure and the residue was recrystallized from EtOH to give the title compound (I) in yield of 85% (m.p. 436 K). Elemental analysis: calculated for C 20 H 19 N 5 O 2 : C, 66.47; H, 5.30; N, 19.38%. Found: C, 65.52; H, 5.63; N, 18.89%. Crystals suitable for singlecrystal X-ray diffraction were obtained from hexane and dichloromethane

S3. Refinement
In the absense of significant anomalous dispersion effects Friedel pairs were merged. An examination of the data using PLATON (Spek, 2009) indicated that the crystal was not twinned. H atoms were placed at calculated positions and treated as riding atoms, with C-H = 0.93-0.98 Å, and U iso (H) = 1.2U eq (C) for CH or 1.5U eq (C) for CH 3 .
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.