organic compounds
Open access
The asymmetric unit of title compound, C18H16O2, contains two molecules with slightly different conformations. In the first molecule, the two phenyl rings make dihedral angles of 84.98 (11)° and the five-membered ring makes dihedral angles of 84.80 (12) and 73.00 (12)° with the phenyl rings; the corresponding angles for the second molecule are 86.74 (11), 81.20 (13) and 71.36 (12)°. O—HO hydrogen bonds between the hydroxy and carbonyl groups are a feature of the crystal packing, which results in chains extending parallel to [100]. Weak C—HO and C—Hπ interactions are also observed.
organic compounds
Open access
The title compound, C8H8N2O4, is almost planar (r.m.s. deviation = 0.037 Å) and an intramolecular N—HO hydrogen bond generates an S(6) ring. In the crystal, inversion dimers linked by pairs of O—HO hydrogen bonds generate R22(8) loops. Intermolecular N—HO hydrogen bonds (involving the same H atom that forms the intramolecular hydrogen bond) link the dimers into infinite sheets lying parallel to (102).