Crystal structure of 6,7-dihydroxy-6,7-dihydro-3H-imidazo[1,2-a]purin-9(5H)-one

The title purine derivative, C7H7N5O3, is an adduct of guanine with glyoxal. In the molecule, the dihydroimidazole 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 molecules are linked by N-H center dot center dot center dot O, O-H center dot center dot center dot N and N-H center dot center dot center dot N hydrogen bonds forming a three-dimensional framework. The crystal packing is reinforced by C-H center dot center dot center dot O hydrogen bonds and by offset pi-pi stacking of the purine ring systems of inversion related molecules [intercentroid distance = 3.4839 (12) angstrom].