Structure-making with 3,5-dinitrosalicylic acid. II. The proton-transfer compounds of 3,5-dinitrosalicylic acid with the monocyclic heteroaromatic amines

The crystal structures of the proton-transfer compounds of 3,5-dinitrosalicylic acid (dnsa) with a series of common monocyclic heteroaromatic amines (pyridine, 4- cyanopyridine, pyridine-4-carboxylic acid, 2,6-diaminopyridine, and 2-aminopyrimidine) have been <LF>determined and the hydrogen-bonding associations in each analyzed. The compounds are the adduct [(C5H6N)(+)(dnsa)(-).(dnsa)] (1), the 1:1 salts [(C6H5N2)(+)(dnsa)(-)] (2), [(C6H6NO2)(+)(dnsa)(-)] (3), [(C5H8N3)(+)(dnsa)(-)] (4), and the 2:2 ethanol hemi-solvate [2(C4H6N3)(+).2(dnsa)(-).0.5(EtOH)] (5). With all compounds, protonation of the hetero-nitrogen atom occurs with subsequent hydrogen bonding to the oxygen atoms of the functional groups of the dnsa anions, resulting in the formation of relatively simple linear or chain polymer associations. Compound (1) represents a rare example of other than a 1:1 association, and the first example of a 2:1 (dnsa/amine) type, with the unusual presence of an additional adduct molecule of dnsa in the structure.