Synthesis, Structure and Performance of an Insensitive Diazonium Inner Salt Energetic Material.

Herein, a novel insensitive diazonium inner salt of 2-nitro-5-oxo[1,2,4]triazolo[1,5-c]pyrimidin-8-diazonium-7-olate (NTPD) was synthesized through a concise three-step route. The structure and performance of this material were comprehensively studied. Single-crystal X-ray diffraction analysis revealed that NTPD possesses a distinctive fused-ring framework featuring an inner salt (zwitterionic) structure, wherein the diazonium and phenolate functionalities are intramolecularly integrated within a compact, highly conjugated heterocyclic system. Furthermore, in comparison with previously reported diazonium compounds, NTPD exhibits a superior combination of enhanced thermal stability and significantly reduced mechanical sensitivity. Specifically, its onset decomposition temperature reaches 206 °C, representing a substantial improvement over conventional diazo derivatives, while its impact sensitivity of 7 J positions it among the least sensitive diazonium-based energetic materials reported to date. The exceptional performance of NTPD is strongly attributed to its nearly planar molecular geometry and the extensive hydrogen-bonding network present within its crystal lattice, which collectively reinforce structural rigidity, enhance packing stability, and effectively dissipate external mechanical stimuli.