title: Cocrystals of 6-propyl-2-thiouracil: N-H···O versus N-H···S hydrogen bonds.
abstract: In order to investigate the relative stability of N-H···O and N-H···S hydrogen bonds, we cocrystallized the antithyroid drug 6-propyl-2-thiouracil with two complementary heterocycles. In the cocrystal pyrimidin-2-amine-6-propyl-2-thiouracil (1/2), C(4)H(5)N(3)·2C(7)H(10)N(2)OS, (I), the `base pair' is connected by one N-H···S and one N-H···N hydrogen bond. Homodimers of 6-propyl-2-thiouracil linked by two N-H···S hydrogen bonds are observed in the cocrystal N-(6-acetamidopyridin-2-yl)acetamide-6-propyl-2-thiouracil (1/2), C(9)H(11)N(3)O(2)·2C(7)H(10)N(2)OS, (II). The crystal structure of 6-propyl-2-thiouracil itself, C(7)H(10)N(2)OS, (III), is stabilized by pairwise N-H···O and N-H···S hydrogen bonds. In all three structures, N-H···S hydrogen bonds occur only within R(2)(2)(8) patterns, whereas N-H···O hydrogen bonds tend to connect the homo- and heterodimers into extended networks. In agreement with related structures, the hydrogen-bonding capability of C=O and C=S groups seems to be comparable.
authors: Institut für Organische Chemie und Chemische Biologie, Goethe-Universität Frankfurt, Frankfurt am Main, Germany.
authors: Maya
authors: M
authors: Tutughamiarso
authors: Ernst
authors: E
authors: Egert
mesh_terms: D013956:Antithyroid Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006860:Hydrogen Bonding; D015394:Molecular Structure; D011441:Propylthiouracil / Q000737:chemistry*
chemical_list: D013956:Antithyroid Agents; D006571:Heterocyclic Compounds; D011441:Propylthiouracil