Related Experiment Video
Updated: May 25, 2026

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Tetra-gonal polymorph of 5,5-dichloro-barbituric acid
Thomas Gelbrich1, Denise Rossi, Ulrich J Griesser
1Institute of Pharmacy, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
Abstract:
The tetra-gonal polymorph of 5,5-dichloro-barbituric acid (m.p. 478 K), C(4)H(2)Cl(2)N(2)O(3), 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 ortho-rhom-bic polymorphs have been reported previously [Gelbrich et al. (2011 ▶). CrystEngComm, 13, 5502-5509].
Related Concept Videos
Predicting Molecular Geometry
Radicals: Electronic Structure and Geometry
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
EDTA: Chemistry and Properties
Hybridization of Atomic Orbitals II
Naming Enantiomers
Hybridization of Atomic Orbitals I

