Abstract
A new cocrystalline salt, 5-bromo-2-aminopyridinium propynoate 7, has been synthesized. Inspection of the crystal structure reveals that the packing differs markedly from that of the chemically analogous species 2-aminopyridinium propynoate 1. While 1 undergoes a thermally-induced Michael addition reaction in the solid state, compound 7 is thermally stable. The lack of similarity between the crystal structures of 1 and 7 may arise from a set of favorable, infinite Br⋯Br interactions (3.82–3.84 Å). Short contacts between acetylenic carbon atoms are also characterized and discussed.