Tetramethylammonium hydrogen terephthalate

Abstract

The asymmetric unit of the title salt, C4H12N +.C8H5O4-, contains one half of a tetramethylammonium cation and one half of a hydrogen terephthalate monoanion. The N atom of the ammonium cation lies on a twofold rotation axis and the centre of mass of the terephthalate anion is on a centre of inversion. In the crystal, the centrosymmetric terephthalate ions are linked by a very short symmetric O - H·O hydrogen bond [O·O = 2.4610 (19) Å] into a one-dimensional polymeric chain along [11̄2]. The tetramethylammonium cations and terephthalate anions are then connected through a pair of bifurcated acceptor C - H̄O hydrogen bonds, generating a three-dimensional supramolecular network. The carboxylate groups at both ends of the terephthalate anion are charge-shared with an equal probability of 0.5.