The salt-type 1 : 2 adduct of meso-5,5,7,12,12,14-hexa-C-methyl-1,4,8,11-tetraazacyclotetradecane (tet-a) and 5-nitroisophthalic acid forms a hydrogen-bonded sheet structure containing two configurational isomers of [(tet-a)H-2](2+)

The title compound, meso-5,7,7,12,14,14-hexamethyl-4,11-diaza-1,8-diazoniacyclotetradecane bis(3-carboxy-5-nitrobenzoate), C16H38N42+.2C(8)H(4)NO(6)(-), is a salt in which the cation is present as two configurational isomers, disordered across a common centre of inversion in P (1) over bar, with occupancies of 0.847 (3) and 0.153 (3). The anions are linked into chains by a single O-H...O hydrogen bond [H...O 1.71 Angstrom, O...O 2.5063 (15) Angstrom and O-H...O 156degrees] and the cations link these anion chains into sheets by means of a range of N-H...O hydrogen bonds [H...O 1.81-2.53 Angstrom, N...O 2.718 (5)-3.3554 (19) Angstrom and N-H...O 146-171degrees].