The variety of possible benzene isomers may provide a fundamental basis for understanding structural and reactivity patterns in organic chemistry. However, the vast majority of these isomers remain unsynthesized, while most of the experimentally known species are only moderately stable. Consequently, there is a high probability that the theoretically proposed isomers would also be barely metastable, a factor that must be taken into account if their creation in the laboratory is sought. In this work, we studied the kinetic stability of all 73 hypothetical tricyclic benzene isomers, especially focusing on their nuclear quantum effects. With this in mind, we evaluated which species are theoretically possible to synthesize, detect, and isolate. Our computations predict that 26% of the previously deemed stable molecules are completely unsynthesizable due to their intrinsic quantum tunnelling instability pushing for their unimolecular decomposition even close to the absolute zero. Five more systems would be detectable, but they will slowly and inevitably degrade, while seven more supposedly stable systems will break apart in barrierless mechanisms.

中文翻译：

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苯异构体中的重原子隧道效应：有多少三环物质是真正稳定的？


各种可能的苯异构体可以为理解有机化学中的结构和反应模式提供基础基础。然而，绝大多数这些异构体仍未合成，而大多数实验已知的异构体仅具有中等稳定性。因此，理论上提出的异构体很可能也几乎是亚稳态的，如果寻求在实验室中创造它们，则必须考虑到这一因素。在这项工作中，我们研究了所有 73 种假设的三环苯异构体的动力学稳定性，特别关注它们的核量子效应。考虑到这一点，我们评估了哪些物种理论上可以合成、检测和分离。我们的计算预测，26% 之前被认为稳定的分子是完全无法合成的，因为它们固有的量子隧道不稳定性推动它们的单分子分解甚至接近绝对零。另外五个系统将是可检测到的，但它们将缓慢且不可避免地退化，而另外七个所谓稳定的系统将在无障碍机制中崩溃。