Date Published: June 01, 2012
Publisher: International Union of Crystallography
Author(s): Graham Smith, Urs D. Wermuth.
In the asymmetric unit of the title co-crystal, C7H5NO4·C12H14N4O2S, there are two independent but conformationally similar heterodimers, which are formed through intermolecular N—H⋯Ocarboxy and carboxyl–pyrimidine O—H⋯N hydrogen-bond pairs, giving a cyclic motif [graph set R22(8)]. The dihedral angles between the rings in the sulfonamide molecules are 78.77 (8) and 82.33 (9)° while the dihedral angles between the ring and the CO2H group in the acids are 2.19 (9) and 7.02 (10)°. A two-dimensional structure parallel to the ab plane is generated from the heterodimer units through hydrogen-bonding associations between NH2 and sulfone groups. Between neighbouring two-dimensional arrays there are two types of aromatic π–π stacking interactions involving either one of the pyrimidine rings and a 4-nitrobenzoic acid molecule [minimum ring centroid separation = 3.5886 (9) Å] or two acid molecules [minimum ring centroid separation = 3.7236 (10) Å].
For background on sulfamethazole as a model for co-crystal formation, see: Caira (2008 ▶). For structures of 1:1 adducts of sulfamethazine with benzoic acid analogues, see: Arman et al. (2010 ▶); Caira (1991 ▶, 1992 ▶); Lynch et al. (2000 ▶); Patel et al. (1988 ▶). For graph-set analysis, see: Etter et al. (1990 ▶).