organic compounds
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The pyrazolo[3,4-d]pyrimidine ring system of the title compound, C12H10N4S, is essentially planar [maximum deviation = 0.025 (1) Å for the C atom bearing the S atom] and almost perpendicular to the phenyl ring [dihedral angle = 71.42 (6)°]. In the crystal, molecules are linked via pairs of N—HN hydrogen bonds, forming inversion dimers.