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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Two polymorphs of 5-cyclohexyl-5-ethylbarbituric acid and their packing relationships with other barbiturates
Thomas Gelbrich1, Isabella Meischberger1, Ulrich J Griesser1
1Institute of Pharmacy, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
Abstract:
Polymorph (Ia) (m.p. 474 K) of the title compound, C(12)H(18)N(2)O(3), displays an N-H...O=C hydrogen-bonded layer structure which contains R(6)(6)(28) rings connecting six molecules, as well as R2(2)(8) rings linking two molecules. The 3-connected hydrogen-bonded net resulting from these interactions has the hcb topology. Form (Ib) (m.p. 471 K) displays N-H...O=C hydrogen-bonded looped chains in which neighbouring molecules are linked to one another by two different R(2)(2)(8) rings. Polymorph (Ia) is isostructural with the previously reported form II of 5-(2-bromoallyl)-5-isopropylbarbituric acid (noctal) and polymorph (Ib) is isostructural with the known crystal structures of four other barbiturates.
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