The mechanism of initial decomposition of energetic compound is crucial to understand the heat release efficiency, impact sensitivity, toxic emission, and so on. In the present study, we progressively explored the thermodynamic and kinetic features of the decomposition of LLM‐105, or 2,6‐diamino‐3,5‐dinitropyrazine‐1‐oxide, a kind of nitro compound in energetic materials using theoretical calculations. The bond dissociation energies (BDEs), bond orders, and the decomposition pathways were investigated by high‐level quantum chemical calculations, and the temperature‐ and pressure‐dependent rate coefficients were computed by Rice‐Ramsperger‐Kassel‐Marcus (RRKM)/master equation simulations. Although thermodynamic properties, for example, BDEs and bond orders, provide preliminary estimates on a possible decomposition mechanism including trigger bonds with relatively low computational costs, kinetic studies are necessary to determine all reaction pathways and competition relationships among various pathways. The potential energy surface at the theoretical level of DLPNO‐CCSD(T)/CBS//M06‐2X‐D3/6‐311++G(d,p) reveals the complicated decomposition mechanism including the bottlenecks of all channels. The computed rate coefficients showthat the reaction channels yielding NO₂ will dominate the initial decomposition at high temperature (>1000 K), while the NO elimination channels play a controlling role at low temperature (<800 K).

中文翻译：

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2,6-二氨基-3,5-二硝基吡嗪-1-氧化物（LLM-105）的分解：从热力学到动力学

高能化合物的初始分解机理对于了解放热效率，撞击敏感性，毒物排放等至关重要。在本研究中，我们通过理论计算逐步探索了LLM-105或2,6-二氨基-3,5-二硝基吡嗪-1-氧化物（一种高能材料中的硝基化合物）分解的热力学和动力学特征。通过高级量子化学计算研究了键离解能（BDEs），键阶和分解途径，并通过Rice-Ramsperger-Kassel-Marcus（RRKM）/ master计算了温度和压力相关的速率系数方程模拟。尽管热力学特性（例如BDE和键序）由于提供了可能的分解机制的初步估计，包括具有相对较低的计算成本的触发键，动力学研究对于确定所有反应途径和各种途径之间的竞争关系是必要的。在理论水平的DLPNO‐CCSD（T）/ CBS // M06‐2X‐D3 / 6‐311 ++ G（d，p）上的势能面揭示了复杂的分解机制，包括所有通道的瓶颈。计算出的速率系数表明反应通道产生NO p）揭示了复杂的分解机制，包括所有通道的瓶颈。计算出的速率系数表明反应通道产生NO p）揭示了复杂的分解机制，包括所有通道的瓶颈。计算出的速率系数表明反应通道产生NO₂将在高温（> 1000 K）中主导初始分解，而NO消除通道在低温（<800 K）中起控制作用。