Crystal structure of 1-methyl-4-methylsulfanyl-1H-pyrazolo[3,4-d]pyrimidine

In the title compound, C7H8N4S, the non-H atoms of the pyrazolo[3,4-d]pyrimidine ring system and the methylsulfanyl group lie on a crystallographic mirror plane. In the crystal, molecules are linked via a number of π–π interactions [centroid–centroid distances vary from 3.452 (7) to 3.6062 (8) Å], forming a three-dimensional structure.

The molecule of the title compound is build up from two fused five-and six-membered rings linked to methylsulfanyl group. All non hydrogen atoms of the molecule are coplanar as shown in Fig. 1. In the crystal, the molecules are linked together by a number of π-π interactions [centroid-centroid distances vary from 3.452 (7) to 3.6062 (8) Å], forming a three-dimensional structure.

S2. Synthesis and crystallization
To a solution of 1H-pyrazolo [3,4-d] pyrimidine-4-thiol (0.5 g, 3.28 mmol) dissolved in DMF (20 ml) was added iodomethane (0.43 ml, 6.62 mmol), potassium carbonate (0.93 g, 7.1 mmol) and a catalytic amount of tetra-n-butylammonium bromide (0.1 g, 0.4 mmol). The mixture was stirred for 48 h and monitored by thin layer chromatography. The mixture was filtered and the solvent was removed in vacuo. The solid obtained was crystallized from ethanol to give the title compound as orange crystals (yield: 65%).

S3. Refinement
The H atoms were located in a difference map and treated as riding with C-H = 0.93 Å (aromatic) and C-H = 0.96 Å (methyl), and with U iso (H) = 1.2 U eq (aromatic) and U iso (H) = 1.5 U eq (methyl).

Figure 1
Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles.

1-Methyl-4-methylsulfanyl-1H-pyrazolo[3,4-d]pyrimidine
Crystal data Hydrogen site location: inferred from neighbouring sites H-atom parameters constrained w = 1/[σ 2 (F o 2 ) + (0.0694P) 2 + 0.3181P] where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.44 e Å −3 Δρ min = −0.29 e Å −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.  (10) 0.2500 0.0349 (4) S1 1.03110 (7) 0.13414 (4) 0.2500 0.0447 (2)