Open AccessCocrystals of 6‐propyl‐2‐thiouracil: N—H...O versus N—H...S hydrogen bonds
Author(s) -
Tutughamiarso Maya,
Egert Ernst
Publication year - 2011
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
eISSN - 1600-5759
pISSN - 0108-2701
DOI - 10.1107/s0108270111037991
Subject(s) - hydrogen bond , cocrystal , thio , chemistry , uracil , stereochemistry , acetamide , crystallography , amine gas treating , molecule , organic chemistry , dna , biochemistry
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.