Further Insights into the Crystal Engineering of High Explosives of 1:2 Salts of the s-Tetrazine Receptor-Picrate Anion Series

Both s-tetrazine and picric acid are widely known compounds in the realm of high-energy materials. We had previously taken an interest—mostly supramolecular, i.e., directed at the elucidation of lone pair–π interactions—in the crystal packing of phases containing s-tetrazine-based cations and picrate anions. Herein we report two novel compounds of this family: H2L4(picr)2 and (H2L5)2(picr)4; the former is a polymorph of a previously reported compound of a homologous host series (3,6-bis(4-morpholinobutyl)-1,2,4,5-tetrazine), the latter a salt of the commercially available 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine. The new phases were investigated via XRD: main interactions, crystal packing, and potential slip planes are discussed. Thermal analysis (DSC/TGA) was conducted for L5 and (H2L5)2(picr)4. Enthalpies of formation (thermochemical cycles/DFT) and in silico explosion parameters (EXPLO5) are reported for all compounds. Overall, the data herein reported improve the understanding of the correlation among supramolecular/packing details and the resulting explosive properties.