3,5-Dinitrosalicylic Acid in Molecular Assembly. III. Proton-Transfer Compounds of 3,5-Dinitrosalicylic Acid with Polycyclic Aromatic and Heteroaromatic Amines, and Overall Series Structural Systematics

Abstract

The crystal structures of the 1:1 proton-transfer compounds of 3,5-dinitrosalicylic acid (dnsa) with a series of common polycyclic aromatic and heteroaromatic amines (quinoline, 1-naphthylamine, 1,2,3,4-tetrahydroquinoline, quinaldic acid, benzimidazole, 1,10-phenanthroline, and 2,2′-bipyridine) have been determined and the hydrogen-bonding associations in each analyzed. The compounds are [(C9H8N)+(dnsa)–] 1, [(C10H10N)+(dnsa)–] 2, [(C9H12N)+(dnsa)–] 3, [(C10H8NO2)+(dnsa)–] 4, [(C7H7N2)+(dnsa)–] 5, [(C12H9N2)+(dnsa)–] 6, and [(C10H9N2)+(dnsa)–] 7. In all compounds, protonation of either the substituent amino group or the hetero-N of the Lewis base occurs, with subsequent hydrogen bonding via this and other hydrogen donors variously to the carboxylate, phenate, and nitro oxygen acceptors of the dnsa anions. The result is the formation of primary N+–H···O associations which with secondary peripheral interactions, which within this set of compounds includes an increased incidence of aromatic C–H···O associations, give framework polymer structures. In three of the compounds [1, 4, and 6], cation–anion π–π interactions are also found. The completion of this series of compounds has now allowed the categorization of the molecular assembly modes in the proton-transfer compounds of 3,5-dinitrosalicylic acid.