A new polymorph of 5-nitro­uracil monohydrate

Pereira Silva, P.S.; Domingos, S.R.; Ramos Silva, M.; Paixão, J.A.; Matos Beja, A.

doi:10.1107/S1600536808014426

Volume 64
Part 6
Page o1091
June 2008

Received 13 May 2008
Accepted 13 May 2008
Online 17 May 2008

Key indicators
Single-crystal X-ray study
T = 293 K
Mean (C-C) = 0.001 Å
R = 0.043
wR = 0.131
Data-to-parameter ratio = 19.4
Details

A new polymorph of 5-nitrouracil monohydrate

P. S. Pereira Silva,^a S. R. Domingos,^a M. Ramos Silva,^a J. A. Paixão ^a and A. Matos Beja ^a ^*

^aCEMDRX, Physics Department, University of Coimbra, P-3004-516 Coimbra, Portugal
Correspondence e-mail: psidonio@pollux.fis.uc.pt

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°.

Related literature

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).

Experimental

Crystal data

C₄H₃N₃O₄·H₂O
M_r = 175.11
Monoclinic, P 2₁ /c
a = 6.2799 (1) Å
b = 7.8481 (2) Å
c = 13.8068 (3) Å
= 93.842 (1)°
V = 678.94 (3) Å³
Z = 4
Mo K radiation
= 0.16 mm^-1
T = 293 (2) K
0.44 × 0.22 × 0.20 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) T_min = 0.890, T_max = 0.969
15135 measured reflections
2232 independent reflections
1918 reflections with I > 2(I)
R_int = 0.018

Refinement

R[F² > 2(F²)] = 0.042
wR(F²) = 0.131
S = 1.00
2232 reflections
115 parameters
H atoms treated by a mixture of independent and constrained refinement
_max = 0.35 e Å^-3
_min = -0.37 e Å^-3

Table 1
Hydrogen-bond geometry (Å, °)

D-HA	D-H	HA	DA	D-HA
N3-H3O2ⁱ	0.86	1.99	2.8503 (13)	173
N1-H1O9ⁱⁱ	0.86	1.88	2.6736 (12)	153
O9-H9AO4ⁱⁱⁱ	0.87 (2)	1.92 (2)	2.7640 (13)	165 (2)
O9-H9AO7ⁱⁱⁱ	0.87 (2)	2.41 (3)	2.9101 (13)	117 (2)
O9-H9BO7^iv	0.84 (3)	2.29 (3)	3.0940 (15)	162 (2)
Symmetry codes: (i) -x, -y, -z+1; (ii) x-1, y, z; (iii) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iv) $[-x+2, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

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 ).

Acknowledgements

This work was supported by Fundação para a Ciência e a Tecnologia (FCT) under project POCI/FIS/58309/2004

References

Bergman, J. G., Crane, G. R., Levine, B. F. & Bethea, C. G. (1972). Appl. Phys. Lett. 20, 21-23.
Bruker (2005). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
Craven, B. M. (1967). Acta Cryst. 23, 376-383.
Pettier, P. R. & Byrn, S. R. (1982). J. Org. Chem. 47, 4671-4676.
Puccetti, G., Perigaud, A., Badan, J., Ledoux, I. & Zyss, J. (1993). J. Opt. Soc. Am. B, 10, 733-744.
Rao, T. S., Rando, R. F., Huffman, J. H. & Revankar, G. R. (1995). Nucleosides Nucleotides, 14, 1997-2008.
Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.
Youping, H., Genbo, S., Bochang, W. & Rihong, J. (1992). J. Cryst. Growth, 119, 393-398.

organic compounds