Effect of counter-ion on packing and crystal density of 5,5′-(3,3′-bi[1,2,4-oxa­diazole]-5,5′-di­yl)bis­(1H-tetra­zol-1-olate) with five different cations

In energetic materials, the crystal density is an important parameter that affects the performance of the material. When making ionic energetic materials, the choice of counter-ion can have detrimental or beneficial effects on the packing, and therefore the density, of the resulting energetic crystal. Presented herein are a series of five ionic energetic crystals, all containing the dianion 5,5′-(3,3′-bi[1,2,4-oxa­diazole]-5,5′-di­yl)bis­(1H-tetra­zol-1-olate), with the following cations: hydrazinium (1) (2N(2)H(5) (+)·C(6)N(12)O(4) (2−)), hydroxyl­ammonium (2) 2NH(4)O(+)·C(6)N(12)O(4) (2−) [Pagoria et al.. (2017). Chem. Heterocycl. Compd, 53, 760–778; included for comparison], di­methyl­ammonium (3) (2C(2)H(8)N(+)·C(6)N(12)O(4) (2−)), 5-amino-1H-tetra­zol-4-ium (4) (2CH(4)N(5) (+)·C(6)N(12)O(4) (2−)·4H(2)O), and amino­guanidinium (5) (2CH(7)N(4) (+)·C(6)N(12)O(4) (2−)). Both the supra­molecular inter­actions and the sterics of the cation play a role in the density of the resulting crystals, which range from 1.544 to 1.873 Mg m(−1). In 5, the tetra­zolate ring is disordered over two positions [occupancy ratio 0.907 (5):0.093 (5)] due to a 180° rotation in the terminal tetra­zole rings.