Redetermination of 2-methyl-4-nitropyridine N -oxide

An improved crystal structure of the title compound, C 6 H 6 N 2 O 3 , is reported. The structure, previously solved [Li et al. (1987). Jiegou Huaxue (Chin. J. Struct. Chem.) , 6 , 20–24] in the orthorhombic space group Pca 2 1 and refined to R = 0.067, has been solved in the orthorhombic space group Pbcm with data of enhanced quality, giving an improved structure ( R = 0.0485). The molecule adopts a planar conformation with all atoms lying on a mirror plane. The crystal structure is composed of molecular sheets extending parallel to the ab plane and connected via C—H...O contacts involving ring H atoms and O atoms of the N -oxide and nitro groups, while van der Waals forces consolidate the stacking of the layers.