Molecular Cocrystals of Carboxylic Acids. XX. The Crystal Structures of 3,5-Dinitrosalicylic Acid and Its Adducts With the Isomeric Monoaminobenzoic Acids

Abstract

The crystal structure of 3,5-dinitrosalicylic acid monohydrate (1) and its adducts with 2- aminobenzoic acid (2-aba) [( dnsa )(2-aba)] (2), 3-aminobenzoic acid (3-aba) [( dnsa )(3-aba)] (3), and 4-aminobenzoic acid (4-aba) [( dnsa )(4-aba)₂] (4), have been determined and the hydrogen bonding associations in each analysed . The acid (1), which is essentially planar, forms strong hydrogen-bonding network associations involving the carboxylic, nitro and phenolic oxygens as well as the lattice water. In all adducts, protonation of the amino group of the second acid occurs, with subsequent hydrogen bonding via all three alkyl ammonium hydrogens to the carboxylic, nitro and phenolic oxygens of dnsa. With the 1:2 adduct (4), only one of the two 4-aba molecules is protonated, these forming a secondary hydrogen-bonded cyclic dimer. A strong intramolecular hydrogen bond between the phenolic proton and the carboxylate group is found in all adducts.