Abstract
The crystal structure of the title compound, C(7)H(5)NO(4), was first reported by Kurahashi, Fukuyo & Shimada [(1967). Bull. Chem. Soc. Jpn, 40, 1296]. It has been re-examined, improving the precision of the derived geometric parameters. The asymmetric unit comprises a non-planar independent mol-ecule, as the nitro and the carb-oxy substituents force each other to be twisted away from the plane of the aromatic ring by 54.9 (2) and 24.0 (2)°, respectively. The mol-ecules form a conventional dimeric unit via centrosymmetric inter-molecular hydrogen bonds.