2-Aminopyridinium-fumarate-fumaric Acid (2/1/1)

Abstract

The title complex, 2C<inf>5</inf>H<inf>7</inf>N<inf>2</inf> +·C<inf>4</inf>H<inf>2</inf>O<inf>4</inf> 2-·C<inf>4</inf>H<inf>4</inf>O<inf>4</inf>, contains cyclic eight-membered hydrogen-bonded rings involving 2-aminopyridinium and fumarate ions. The fumaric acid molecules and fumarate ions lie on inversion centers and are linked into zigzag chains by O - H⋯O hydrogen bonds. The dihedral angle between the pyridinium ring and the hydrogen-bonded fumarate ion is 7.60 (4)°. The fumarate anion is linked to the pyridinium cations by intermolecular N - H⋯O hydrogen bonds. The heterocycle is fully protonated, thus enabling amine-imine tautomerization.