Two 3-amino-1H-pyrazol-2-ium salts containing organic anions, and an orthorhombic polymorph of 3-amino-1H-pyrazol-2-ium nitrate

Abstract

Co-crystallization from methanol of 3-amino-1H-pyrazole with 3,5-dinitro-benzoic acid produces 3-amino-1H-pyrazol-2-ium 3,5-dinitrobenzoate mono-hydrate, C3H6N3+.C7H3N2O6-center dot H2O, (I), while similar co-crystallization of this pyrazole with an equimolar quantity of fumaric acid produces bis(3-amino-1H-pyrazol- 2-ium) fumarate-fumaric acid (1/1), 2C(3)H(6)N(3)(+)center dot C4H2O42-center dot C4H4O4, (II). The reaction of 3-amino-1H-pyrazole with a dilute solution of nitric acid in methanol yields a second, orthorhombic polymorph of 3-amino-1H-pyrazol-2-ium nitrate, C3H6N3+center dot NO3-, (III). In each of (I)-(III), the bond distances in the cation provide evidence for extensive delocalization of the positive charge. In each of (I) and (II), an extensive series of O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds links the components into complex sheets, while in the structure of (III), the ions are linked by multiple N-H center dot center dot center dot O hydrogen bonds into a threedimensional arrangement. Comparisons are made with the structures of some related compounds.