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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Toward Understanding the Decomposition of Carbonyl Diazide (N-3)(2)C=O and Formation of Diazirinone cycl-N2CO: Experiment and Computations
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Toward Understanding the Decomposition of Carbonyl Diazide (N-3)(2)C=O and Formation of Diazirinone cycl-N2CO: Experiment and Computations

机译：理解羰基二叠氮化物（N-3）（2）C = O的分解和重氮醌环-N2CO的形成：实验和计算

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摘要

Carbonyl diazide, (N-3)(2)CO (I), is a highly explosive compound. The isolation of the substance in a neat form was found to provide unique access to two other high-energy molecules, namely, N-3-NCO (III) and cycl-N2CO (IV), among the decomposition products of (I). To understand the underlying reaction mechanism, the decomposition reactions including the thermal conversion of two conformers of (I) were revisited, and the potential energy surface (PES) was computationally explored by using the methods of B3LYP/6-311+G(3df) and CBS-QB3. The most stable syn-syn structure (I) readily converts into the syn-anti conformer (Delta H-exptl = 1.1 +/- 0.5 kcal mol(-1)), which undergoes decomposition in two competing pathways: a concerted path to N-3-NCO (III) or a stepwise route to (III) via the nitrene intermediate N3C(O)N (1)(II). The calculated activation barriers (E-a) are almost the same (similar to 33 kcal mol(-1), B3LYP/6-311+G(3df)). Further decomposition of (III) occurs through a concerted fragmentation into 2 N-2 + CO with a moderate E-a of 22 kcal mol(-1), and this process is compared to the isoelectronic species N-3-N-3 -> 3 N-2 (E-a = 17 kcal mol(-1)) and OCN-NCO -> N-2 + 2 CO (61 kcal mol(-1)). No low-energy pathway leading to (IV) was found on the singlet PES. However, the intervention of triplet ground-state (3)(II) from the initially generated (1)(II) through an intersystem crossing (ISC) offers a likely approach to (IV); that is, (3)(II) can decompose in a concerted process (E-a = 30 kcal mol(-1)) by eliminating one N-2 to yield the disfavored OCNN (3)(VI). A careful intrinsic reaction coordinate analysis and a combined energy scan of the N-C-N angle reveals a bifurcation point on this triplet PES, which allows a spin crossover to the singlet PES along the reaction coordinate and eventually leads to the formation of the metastable diazirinone (IV).
机译：羰基二叠氮化物（N-3）（2）CO（I）是一种高度爆炸性的化合物。发现以纯净形式分离出该物质可提供独特的途径来接近（I）分解产物中的另外两个高能分子，即N-3-NCO（III）和环-N2CO（IV）。为了理解潜在的反应机理，重新讨论了包括（I）的两个构象异构体的热转化在内的分解反应，并使用B3LYP / 6-311 + G（3df）的方法对势能面（PES）进行了计算探索。和CBS-QB3。最稳定的syn-syn结构（I）可以轻松转变为syn-anti构象异构体（Delta H-exptl = 1.1 +/- 0.5 kcal mol（-1）），它在两个竞争途径中经历分解：向N的协同途径-3-NCO（III）或通过亚硝基中间体N3C（O）N（1）（II）逐步生成（III）。计算的激活势垒（E-a）几乎相同（类似于33 kcal mol（-1），B3LYP / 6-311 + G（3df））。 （III）的进一步分解通过协同裂解为2 N-2 + CO而中度Ea为22 kcal mol（-1），并且将该过程与等电子物质N-3-N-3-> 3进行了比较N-2（Ea = 17 kcal mol（-1））和OCN-NCO-> N-2 + 2 CO（61 kcal mol（-1））。在单重态PES上未发现导致（IV）的低能途径。然而，通过系统间交叉（ISC）从最初生成的（1）（II）对三重态基态（3）（II）的干预提供了一种可能的方法（IV）;也就是说，（3）（II）可以通过消除一个N-2产生不利的OCNN（3）（VI），在协调一致的过程中分解（E-a = 30 kcal mol（-1））。仔细的内在反应坐标分析和NCN角的组合能量扫描揭示了该三重态PES上的分叉点，该分支点使自旋PES沿着反应坐标自旋交叉，最终导致形成亚稳的重氮基（IV） 。

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