Crystal structure of 2-amino-5-nitropyridinium sulfamate

Abstract

The title molecular salt, C5H6N3O2+ ·H2NO3S−, was obtained from the reaction of sulfamic acid with 2-amino-5-nitropyridine. A proton transfer from sulfamic acid to the pyridine N atom occurred, resulting in the formation of a salt. As expected, this protonation leads to the widening of the C—N—C angle of the pyridine ring, to 122.9 (3)°, with the pyridinium ring being essentially planar (r.m.s. deviation = 0.025 Å). In the crystal, the ion pairs are joined by three N—H...O and one N—H...N hydrogen bonds in which the pyridinium N atom and the amino N atom act as donors, and are hydrogen bonded to the carboxylate O atoms and the N atom of the sulfamate anion, thus generating an R33(22) ring motif. These motifs are linked by further N—H...O hydrogen bonds enclosing R33(8) loops, forming sheets parallel to (100). The sheets are linked via weak C—H...O hydrogen bonds, forming a three-dimensional structure. The O atoms of the nitro group are disordered over two sets of sites with a refined occupancy ratio of 0.737 (19):0.263 (19).

Keywords

• crystal structure
• sulfamic acid
• 2-amino-5-nitropyridine
• sulfamate
• 2-amino-5-pyridinium
• molecular salt
• hydrogen bonding.