Crystal structure of 6,7-dihy-droxy-6,7-di-hydro-3H-imidazo[1,2-a]purin-9(5H)-one.

The title purine derivative, C7H7N5O3, is an adduct of guanine with glyoxal. In the mol-ecule, the di-hydro-imidazole ring adopts a twisted conformation on the C-C bond, and the two hydroxyl groups lie on opposite sides of the mean plane of the ring. In the crystal, the mol-ecules are linked by N-H⋯O, O-H⋯N and N-H⋯N hydrogen bonds forming a three-dimensional framework. The crystal packing is reinforced by C-H⋯O hydrogen bonds and by offset π-π stacking of the purine ring systems of inversion related mol-ecules [inter-centroid distance = 3.4839 (12) Å].