Crystal structures of 2-methylpyridinium hydrogen 2,3-bis(4-methylbenzoyloxy)succinate and bis-[4-methylpyridinium hydrogen 2,3-bis(4-methylbenzoyloxy)succinate] pentahydrate

Abstract

The title salt (I), C6H8N+·C20H17O8−, comprises a 2-methylpyridinium cation and a 2,3-bis(4-methylbenzoyloxy)succinate mono-anion while the salt (II), 2C6H8N+·2C20H17O8−·5H2O, consists of a pair of 4-methylpyridinium cations and 2,3-bis(4-methylbenzoyloxy)succinate mono-anions and five water molecules 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 molecules 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 interactions, 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 molecules, giving a two-dimensional network across (001). The crystal structure is also stabilized by weak C—H...O and C—H...π interactions.