Tabun (ethyl N,N-dimethylphosphoramidocyanidate), or GA, is a chemical warfare nerve agent produced during the World War II. The synthesis of its analogs is rather simple; thus, it is a significant threat. Furthermore, experiments with tabun and other nerve agents are greatly limited by the involved life risks and the severe restrictions imposed by the Chemical Weapons Convention. For these reasons, accurate theoretical assignment of fragmentation pathways can be especially important. In this work, we employ the Quantum Chemistry Electron Ionization Mass Spectra method, which combines molecular dynamics, quantum chemistry methods, and stochastic approaches, to accurately investigate the electron ionization/mass spectrometry (EI/MS) fragmentation spectrum and pathways of the tabun molecule. We found that different rearrangement reactions occur including a McLafferty involving the nitrile group. An essential and characteristic pathway for identification of tabun and analogs, a two-step fragmentation producing the m/z 70 ion, was confirmed. The present results will be also useful to predict EI/MS spectrum and fragmentation pathways of other members of the tabun family, namely, the O-alkyl/cycloalkyl N,N-dialkyl (methyl, ethyl, isopropyl, or propyl) phosphoramidocyanidates.

中文翻译：

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塔邦电子电离质谱的分子动力学模拟。

Tabun（N，N-二甲基磷酰胺基氰酸氰乙酯）或GA，是第二次世界大战期间生产的化学战神经毒剂。其类似物的合成非常简单。因此，这是一个重大威胁。此外，由于涉及生命危险以及《化学武器公约》施加的严格限制，使用塔邦和其他神经毒剂的实验受到极大的限制。由于这些原因，对裂解途径的准确理论分配可能特别重要。在这项工作中，我们采用了量子化学电子电离质谱方法，该方法结合了分子动力学，量子化学方法和随机方法，可以准确地研究电子电离/质谱（EI / MS）的碎裂谱和禁忌分子的途径。我们发现发生了不同的重排反应，包括涉及腈基的McLafferty。证实了用于鉴定塔伯恩和类似物的主要和特征途径，即产生m / z 70离子的两步裂解。本结果也可用于预测塔宾家族其他成员的EI / MS光谱和碎裂途径，即O-烷基/环烷基N，N-二烷基（甲基，乙基，异丙基或丙基）磷酰胺基氰化物。