Redetermination of 4-cyano­pyridine N-oxide

In the title pyridine N-oxide derivative, C₆H₄N₂O, the 4-cyano substituent almost lies in the mean plane of the pyridine ring (r.m.s deviation of all non-H atoms = 0.004 Å). This redetermination results in a crystal structure with significantly higher precision [N—O bond length is 1.2997 (15) compared with 1.303 (5) Å in the original] than the original determination, which was recorded using the multiple-film technique and visually estimated intensities [Hardcastle et al. (1974). J. Cryst. Mol. Struct. 4, 305–311]. The crystal structure features weak C—H...O and C—H...N inter­actions, which lead to the formation of chains that inter­sect each other parallel to (001).