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Acta Cryst. (2012). E68, o235-o236 [ doi:10.1107/S1600536811054626 ]
Abstract: The tetragonal polymorph of 5,5-dichlorobarbituric acid (m.p. 478 K), C4H2Cl2N2O3, forms an N-H
O hydrogen-bonded tape structure along [001]. Two tapes related by a twofold rotation axis are associated via ClO contacts [3.201 (1) Å], and four such chain pairs are arranged around a fourfold roto-inversion axis. The crystal structures of the monoclinic and orthorhombic polymorphs have been reported previously [Gelbrich et al. (2011). CrystEngComm, 13, 5502-5509].
Online 23 December 2011
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