Salt Formation, to Realize a Good Combination of High Energy and Low Sensitivity of Nitroform-Based Energetic Compounds

Energetic salts constitute an important issue in the field of energetic materials. In this research, the series of energetic salts 5–8 with nitroform structures were obtained by a single-displacement reaction, and their crystal structures were fully characterized by X-ray single-crystal diffraction. As energetic compounds, their energy performance and sensitivity to mechanical stimuli have been explored. These compounds not only exhibit excellent detonation performance (Dv = 8.45–9.13 km s–1 and P = 30.5–37.4 GPa) and extremely high specific impulse (Isp = 262.63–277.42 s) but also show low sensitivity to mechanical stimuli. According to the crystallographic data, the relationship between molecular structure and sensitivity has been explored. The results show that the positive electrostatic potential near the nitroform and the interaction between the intermolecular nitro oxygen atoms (O···O interaction) are significantly reduced after salt formation. In addition, this trend of change is consistent with the sensitivity distribution of these energetic salts (the impact sensitivity decreased from 5 to 15 J and the friction sensitivity decreased from 100 to 240 N). This study not only provides ideas for the molecular design of high-specific-impulse energetic compounds but also reveals the relationship between the structure and sensitivity of nitroform energetic compounds from the perspective of crystallography.