Abstract: | The title compounds, 4‐hydroxy‐5‐oxo‐1,3,6‐cycloheptatriene‐1‐carbonitrile, C8H5NO2, (I), and 2‐hydroxy‐5‐nitro‐2,4,6‐cycloheptatrien‐1‐one, C7H5NO4, (II), have intra‐ and intermolecular hydrogen bonds. The structure of (II) contains two crystallographically independent molecules, (IIa) and (IIb). An intermolecular π–π interaction and an intermolecular NO2?π–π interaction are present in (I) and (II), respectively. |