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 Cl⋯O 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].
Highlights
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 Cl O contacts [3.201 (1) Å], and four such chain pairs are arranged around a fourfold rotoinversion axis
Kahlenberg for access to the X-ray instrument used in this study
Summary
R factor = 0.020; wR factor = 0.050; data-to-parameter ratio = 12.2. 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 Cl O contacts [3.201 (1) Å], and four such chain pairs are arranged around a fourfold rotoinversion axis. The crystal structures of the monoclinic and orthorhombic polymorphs have been reported previously [Gelbrich et al (2011).
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