Hydrogen-bonding interactions in the salts 2,4,6-triaminopyrimidin-1-ium sorbate dihydrate, 2,4,6-triaminopyrimidin-1-ium N-phenylantharanilate and 2,4,6-triaminopyrimidin-1-ium p-toluenesulfonate.

Abstract

Three salts, namely, 2,4,6-triaminopyrimidin-1-ium sorbate dihydrate, C₄H₈N₅⁺·C₆H₇O₂^-·2H₂O, (I), 2,4,6-triaminopyrimidin-1-ium N-phenylanthranilate, C₄H₈N₅⁺·C₁₃H₁₀NO₂^-, (II), and 2,4,6-triaminopyrimidin-1-ium p-toluenesulfonate, C₄H₈N₅⁺·C₇H₇O₃S^-, (III), were synthesized, characterized by X-ray diffraction techniques and their supramolecular interactions investigated. In all three crystal structures, protonation of the pyrimidine moiety occurs at the N1 position and is reflected in a widening of the C-N-C bond angle. In salts (I)-(III), the primary acid-base interaction occurs through a pair of N-H...O hydrogen bonds to give a heterodimeric R₂²(8) synthon. Salts (II) and (III) form a discrete centrosymmetric base pair that produces a homodimeric R₂²(8) synthon and salt (I) forms a water-mediated base pair resulting in a tetrameric R₄⁴(12) synthon. The supramolecular patterns exhibited by sulfonate salt (III) mimic the patterns of carboxylate salt (II) and both exhibit a DADA array (D = donor and A = acceptor) quadruple hydrogen-bonded pattern. The crystal structures of salts (I) and (III) are stabilized by offset and face-to-face aromatic π-π stacking interactions, respectively. The resulting architectures in salts (I)-(III) are a supramolecular sheet with a rosette-like architecture in (I), a supramolecular sheet-like architecture in (II) and a three-dimensional supramolecular network in (III).