Crystal structures of 2-methyl-pyridinium hydrogen 2,3-bis-(4-methyl-benzo-yloxy)succinate and bis-[4-methyl-pyridinium hydrogen 2,3-bis-(4-methyl-benzo-yloxy)succinate] penta-hydrate.

Abstract

The title salt (I), C6H8N+·C20H17O8-, comprises a 2-methyl-pyridinium cation and a 2,3-bis-(4-methyl-benzo-yloxy)succinate mono-anion while the salt (II), 2C6H8N+·2C20H17O8-·5H2O, consists of a pair of 4-methyl-pyridinium cations and 2,3-bis-(4-methyl-benzo-yloxy)succinate mono-anions and five water mol-ecules of solvation in the asymmetric unit. In (I), the dihedral angle between the aromatic rings of the anion is 40.41 (15)°, comparing with 43.0 (3) and 85.7 (2)° in the conformationally dissimilar anion mol-ecules in (II). The pyridine ring of the cation in (I) is inclined at 23.64 (16) and 42.69 (17)° to the two benzene moieties of the anion. In (II), these comparative values are 4.7 (3), 43.5 (3)° and 43.5 (3), 73.1 (3)° for the two associated cation and anion pairs. The crystal packing of (I) is stabilized by inter-ionic N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds as well as weak C-H⋯π inter-actions, linking the ions into infinite chains along [100]. In the crystal packing of (II), the anions and cations are also linked by N-H⋯O and O-H⋯O hydrogen bonds involving also the water mol-ecules, giving a two-dimensional network across (001). The crystal structure is also stabilized by weak C-H⋯O and C-H⋯π inter-actions.