Frenklach Alexander, Amlani Hila, Kozuch Sebastian
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 841051, Israel.
J Am Chem Soc. 2024 May 1;146(17):11823-11834. doi: 10.1021/jacs.4c00608. Epub 2024 Apr 18.
Several cycloreversion reactions of the retro-Diels-Alder type were computationally assessed to understand their quantum tunneling (QT) reactivity. N, CO, and other leaving groups were considered based on their strong exothermicity, as it reduces their thermodynamic and kinetic stabilities. Our results indicate that for many of these reactions, it is essential to take into account their QT decomposition rate, which can massively weaken their molecular stability and shorten their half-lives even at deep cryogenic temperatures. In practical terms, this indicates that many supposedly stable molecules will actually be unsynthesizable or unisolable, and therefore trying to prepare or detect them would be a futile attempt. In addition, we discuss the importance of tunneling to correctly understand the enthalpy of activation and the collective atomic effect on the tunneling kinetic isotope effects to test if third-row atoms can tunnel in a chemical reaction. This project raises the question of the importance of chemistry to guide chemistry, especially in cases where the latter cannot solve its own uncertainties.
为了理解它们的量子隧穿（QT）反应活性，对几种逆狄尔斯-阿尔德类型的环化反转反应进行了计算评估。基于N、CO和其他离去基团的强放热性对其进行了研究，因为这会降低它们的热力学和动力学稳定性。我们的结果表明，对于许多这类反应，必须考虑它们的QT分解速率，即使在深低温下，这也会极大地削弱它们的分子稳定性并缩短它们的半衰期。实际上，这表明许多所谓稳定的分子实际上将无法合成或分离，因此试图制备或检测它们将是徒劳的尝试。此外，我们讨论了隧穿对于正确理解活化焓的重要性，以及集体原子效应在隧穿动力学同位素效应方面的作用，以检验第三周期原子在化学反应中是否能够隧穿。该项目提出了化学指导化学的重要性问题，特别是在后者无法解决自身不确定性的情况下。
