Crystal structure of 1-phenyl-1H-pyrazolo-[3,4-d]pyrimidin-4(5H)-one

Heating of 5-amino-1-phenyl-1H-pyrazole-4-carbo-nitrile in the presence of formic acid yielded the title compound, C₁₁H₈N₄O. The pyrazolo-[3,4-d]pyrimidine ring system forms a dihedral angle of 34.72 (6)° with the phenyl ring. In the crystal, classical N-H⋯O and non-classical C-H⋯O and C-H⋯N inter-molecular inter-actions result in the formation of supra-molecular bands extending parallel to the a axis. Additional π⋯π inter-actions between pyrimidine and pyrazole rings, and C-H⋯π inter-actions between neighboring phenyl rings consolidate the packing.