This work studies the photochemical and thermal decompositions of azidoacetonitrile (N₃CH₂CN) from both the experimental and theoretical points of view. The data of the photochemical experiments are taken from the literature, while the thermal decomposition have been carried out by us. In addition, we have performed ab initio calculations of the multiconfigurational type [complete active space self‐consistent field (CASSCF) and the multistate multireference perturbation theory (MS‐CASPT2)]. It is found that the first step of both type of decompositions is N₂ elimination and formation of closed shell singlet nitrene. Afterwards, the nitrene tends to rapidly rearrange into formimidoyl cyanide (HNCHCN). As both reactions progress, the imine isomerizes into formimidoyl isocyanide (HNCHNC). The photoisomerization of the imine takes places thorough a conical intersection, while the same reaction on the ground electronic state occurs via a conventional transition state. The last step of the global reaction is decomposition of the imines into HCN and CNH. In photochemical conditions, the conjunction of the imines and its dissociation products (HCN and CNH) yields adenine

中文翻译：

---

对叠氮基乙腈的热和光化学反应机理的见解。光谱和MS-CASPT2计算。

这项工作从实验和理论的角度研究了叠氮基乙腈（N ₃ CH ₂ CN）的光化学分解和热分解。光化学实验的数据取自文献，而热分解是由我们进行的。此外，我们已经进行了多配置类型的从头算[完全活动空间自洽场（CASSCF）和多状态多参考扰动理论（MS-CASPT2）]。发现两种分解的第一步都是N ₂消除并形成闭壳单线态氮。此后，腈趋于迅速重排成甲酰亚胺基氰化物（HNCHCN）。随着两个反应的进行，亚胺异构化为甲酰亚胺基异氰酸酯（HNCHNC）。亚胺的光异构化通过圆锥形相交进行，而对基电子态的相同反应是通过常规过渡态发生的。总体反应的最后一步是将亚胺分解为HCN和CNH。在光化学条件下，亚胺及其解离产物（HCN和CNH）的结合产生腺嘌呤