Bis(tetramethylamonium) bis(2,4,5-carboxybenzoate)–benzene-1,2,4,5-tetracarboxylic acid (1/1)

The asymmetric unit of the title compound, 2C4H12N+·2C10H5O8 ·C10H6O8, consists of a tetramethylamonium cation, an anion derived from the singly deprotonated pyromellitic acid anion, 2,4,5-carboxybenzoate (H3bta ), and one-half of a benzene-1,2,4,5-tetracarboxylic acid (H4bta) molecule, which has the centroid of the aromatic ring positioned at a crystallographic centre of inversion. The H4bta and H3bta residues are involved in an extensive intermolecular O—H...O hydrogen-bonding network, which leads to a three-dimensional supramolecular structure containing one-dimensional channels running parallel to the [001] crystallographic direction. These channels house the tetramethylamonium cations.