Received 13 May 2008
In the title compound, C4H3N3O4·H2O, molecules of 5-nitrouracil are hydrogen bonded in pairs across crystallographic centers of symmetry. The resulting dimers are also hydrogen bonded to the water molecules, forming a three-dimensional network. The pyrimidine ring is almost planar (with a maximum deviation of 0.0156 (9) Å for the one of the N atoms) and the nitro group is rotated by 12.4 (1)° out of the uracil plane, while in the other polymorph the value for the same angle is 5°.
For the non-linear optical properties of 5-nitrouracil, see: Bergman et al. (1972); Puccetti et al. (1993); Youping et al. (1992). For the crystal structure of another polymorph, see: Craven (1967). For related literature, see: Pettier & Byrn (1982); Rao et al. (1995).
Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT2713 ).
This work was supported by Fundação para a Ciência e a Tecnologia (FCT) under project POCI/FIS/58309/2004
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