Non-Centrosymmetric Polymorphs of Hydrazinium 4H-[1,2,3]Triazolo[4,5-c][1,2,5]Oxodiazol-5-Oxide Salt

Abstract

A new β-polymorph of hydrazinium salt of [1,2,3]triazolo[4,5-c][1,2,5]oxodiazol-5-oxide is obtained and characterized by single crystal X-ray diffraction. The new form crystallizes in chiral space group P1, as well as the previously described α-polymorph (P2₁). The analysis of crystal packings of polymorphs reveals that they have both cation-anion, anion-anion, and cation-cation contacts. Both forms contain identical H-bonded supramolecular synthons: the \(\text{R}_{2}^{2}(7)\) cation-anion associate and infinite chains of hydrazinium cations formed by translation symmetry. The analysis of the Cambridge Crystallography Data Center shows that similar cationic chains occur in 29% of structures of hydrazinium salts, which indicates their abundance. Explanation is proposed for the crystallization of both polymorphs in non-centrosymmetric space groups, which is based on a combination of 1D and 2D non-centrosymmetric supramolecular synthons: chains and layers. The cohesion energies of polymorphs calculated by the quantum chemical simulation of crystals differ by 0.6 kcal/mol.