Experimental

R factor = 0.072; wR factor = 0.186; data-to-parameter ratio = 17.0. The asymmetric unit of the title compound, C7H8N2O3, contains two approximately planar molecules (r.m.s. devia-tions = 0.058 and 0.070 Å). In the crystal, molecules are linked into [010] chains by way of alternating N—H O and N— H (N,O) hydrogen-bond linkages. Related literature For a related structure, see: Li & Jian (2010)