6-Oxo-1,6-dihydropyridine-3-carboxylic acid

The title compound, C6H5NO3, commonly known as 6-hydroxynicotinic acid, is found to be a tautomer of it. Four molecules, all adopting a planar conformation, are found in the asymmetric unit. The compound forms hydrogen-bonded sheets parallel to the [ 001] direction via intermolecular N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds. Each sheet consists of interconnected dimers created by R-2(2)(8) N-H center dot center dot center dot O hydrogen-bonded motifs and infinite chains formed by C( 7) hydrogen-bonded motifs. Alternatively, these sheets can be viewed as infinitely fused 32-membered hydrogen-bonded rings.