Supramolecular interactions in 2,6-diamino-4-chloropyrimidin-1-ium 5-chlorosalicylate and bis(2,6-diamino-4-chloropyrimidin-1-ium) naphthalene-1,5-disulfonate

Abstract

The crystals of two new salts, 2,6-diamino-4-chloropyrimidin-1-ium 5-chlorosalicylate, C4H6ClN4 +·C7H4ClO3 −, (I), and bis(2,6-diamino-4-chloropyrimidin-1-ium) naphthalene-1,5-di-sulfonate, 2C4H6ClN4 +·C10H6O6S2 2−, (II), have been synthesized and characterized by single-crystal X-ray diffraction. In both compounds, the N atom of the pyrimidine group in between the amino substituents is protonated and the pyrimidinium cation forms a pair of N—H...O hydrogen bonds with the carboxylate/sulfonate ion, leading to a robust R 2 2(8) motif (supramolecular heterosynthon). In compound (I), a self-complementary base pairing involving the other pyrimidinium ring nitrogen atom and one of the amino groups via a pair of N—H...N hydrogen bonds [R 2 2(8) homosynthon] is also present. In compound (II), the crystallographic inversion centre coincides with the inversion centre of the naphthalene-1,5-disulfonate ion and all the sulfonate O atoms are hydrogen-bond acceptors, generating fused-ring motifs and a quadruple DDAA array. A halogen-bond (Cl...Cl) interaction is present in (I) with a distance and angle of 3.3505 (12) Å and 151.37 (10)°, respectively. In addition, a C—Cl...π interaction and a π–π interaction in (I) and a π–π interaction in (II) further stabilize these crystal structures.