A series of polynitro-substituted 5,6-dihydrodiimidazo[1,2-a:2′,1′-c]pyrazine energetic compounds were synthesized by cyclization and nitration of biimidazole. All newly synthesized compounds were fully characterized by infrared spectroscopy, ¹H and ¹³C nuclear magnetic resonance spectroscopy, and elemental analysis. Single-crystal X-ray diffraction, iso-chemical shielding surfaces, localized orbital locator-π, Hirshfeld surface analysis, and noncovalent interactions were employed to investigate the structures of 1–6. It is worth mentioning that compounds 3–6 are all thermally stable, with onset decomposition temperatures of 200–330 °C (DSC). Moreover, impact and friction sensitivity test results show that they are insensitive. Energy-related parameters, including densities, heats of formation, and detonation properties, were predicted according to the classical methods. In addition, the influence of the number and position of substituted nitro groups on density, heat of formation, and detonation performance was theoretically established. The superior detonation performances and good stabilities make compounds 4 and 5 useful as replacements for TNT.

中文翻译：

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多硝基取代的 5,6-二氢二咪唑并[1,2-a:2',1'-c]吡嗪高能化合物的合成、结构和性质

通过联咪唑的环合硝化合成了一系列多硝基取代的5,6-二氢二咪唑并[1,2- a :2',1' - c ]吡嗪含能化合物。所有新合成的化合物均通过红外光谱、¹ H 和¹³ C 核磁共振光谱和元素分析进行​​了充分表征。采用单晶 X 射线衍射、等化学屏蔽表面、局部轨道定位器-π、Hirshfeld 表面分析和非共价相互作用来研究1-6的结构。值得一提的是化合物3-6都是热稳定的，起始分解温度为 200–330 °C (DSC)。此外，冲击和摩擦敏感性测试结果表明它们是不敏感的。根据经典方法预测了与能量相关的参数，包括密度、形成热和爆轰特性。此外，从理论上建立了取代硝基的数量和位置对密度、生成热和爆轰性能的影响。优异的爆轰性能和良好的稳定性使化合物4和5可用作 TNT 的替代品。