(IUCr) Crystallography Journals Online

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Acta Cryst. (2004). E60, o1433-o1436 [ doi:10.1107/S1600536804018367 ]

6-Methyl-2-pyridone pentahydrate

W. Clegg and G. S. Nichol

Abstract: Crystals of the title compound, C₆H₇NO·5H₂O, were grown over a period of several weeks from an aqueous solution of the commercial compound. The molecule crystallizes in space group P $\overline 1$ and there are two independent 6-methyl-2-pyridone (Hmhp) molecules in the asymmetric unit, together with ten molecules of water. Packing diagrams reveal stacks of hydrogen-bonded Hmhp dimers surrounded by channels of water molecules. The Hmhp molecules pack with face-to-face [pi] - [pi] stacking, a common feature of pyridone crystal structures. Each water molecule serves twice as hydrogen-bond donor and twice as acceptor, and is thus pseudo-tetrahedral. The water molecules are arranged in hydrogen-bonded five- and six-membered rings and the rings are fused together, with the five-membered rings adopting an envelope conformation and the six-membered rings adopting either a chair or boat conformation. This structure is further evidence that Hmhp exists in the solid state as the pyridone tautomer and not the pyridinol tautomer.

Online 31 July 2004