Molecular and Crystal Structure of Two Organic Acid–Base Salts from 2-amino-6-methylpyridine and meta and para Methylbenzoic Acids

Abstract

Two crystalline organic acid-base salts 2-amino-6-methylpyridinium 3-methylbenzoate [(2A6MP)+.(3MBA)−] (1) and 2-amino-6-methylpyridinium 4-methylbenzoate [(2A6MP)+.(4MBA)−] (2) were obtained from self-assembly of the corresponding acidic components with the 2-amino-6-methylpyridine, and their structures were fully characterized by FTIR, 1H NMR, 13C NMR spectroscopic techniques, and single crystal X-ray diffraction. Both compounds are ionic, with proton transfer occurring to the pyridine nitrogen (NH) of 2-amino-6-methylpyridinium moiety. These structures adopted supramolecular heterosynthons [R22(8)]. The compound (1) crystallizes in the monoclinic crystal system with the space group P21/c with a = 7.3175(3) Å, b = 23.6223(12) Å, c = 7.5523(4) Å, β = 106.323(3) °, v = 1252.84 (11) Å3, Z = 4. The compound (2) crystallizes in the orthorhombic space group P212121 with unit cell dimensions a = 7.1580(7) Å, b = 13.4242(13) Å, c = 14.3238(14) Å, α = β = γ = 90°, v = 1375.4(2) Å3, Z = 4. Supramolecular architectures of the compounds 1 and 2 involve N—H…O hydrogen bonds as well as other nonvocalent associations. The role of these noncovalent interactions in the crystal packing is analyzed. For the presence of these weak noncovalent interactions, both compounds displayed two and three dimensional framework structure.