Two- and three-dimensional hydrogen-bonded structures in the 1:1 proton-transfer compounds of 4,5-dichlorophthalic acid with the isomeric monoaminobenzoic acids

摘要

The crystal structures of the 1:1 proton-transfer compounds of 4,5-dichlorophthalic acid with the isomeric monoaminobenzoic acids, namely the hydrate 2-carboxy-4,5-dichlorobenzoate dihydrate, C7H8NO2^+^ . C8H3Cl2O4^-^. 2H2O (I), and the anhydrous salts 3-carboxyanilinium 2-carboxy-4,5-dichlorobenzoate, C7H8NO2^+^. C8H3Cl2O4^-^, (II), and 4-carboxyanilinium 2-carboxy-4,5-dichlorobenzoate, C7H8NO2^+^. C8H3Cl2O4^-^, (III), have been determined at 130 K. Compound (I) has a three-dimensional sheet structure, while (II) and (III) are three-dimensional. All three compounds feature sheet substructures formed through anilinium N^+^-H...O(carboxyl) and anion carboxylic acid O-H...O(carboxyl) interactions and, in the case of (I), additionally linked through the donor and acceptor associations of the solvent water molecules. However, (II) and (III) have additional lateral extensions of these substructures through cyclic R^2^/2(8) associations involving the carboxylic acid groups of the cations. Also, (II) and (III) have cation-anion pi--pi aromatic ring interactions. This work provides further examples illustrating the regular formation of network substructures in the proton-transfer salts of 4,5-dichlorophthalic acid with the bifunctional aromatic amines.