Zhou Yangyu, Fan Wenbin, Tang Jingjing, Fang Wei, Zhou Mingfei
Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200438, China.
J Am Chem Soc. 2024 Oct 2;146(39):26719-26725. doi: 10.1021/jacs.4c06137. Epub 2024 Sep 18.
Quantum mechanical tunneling (QMT) has long been recognized as crucial for understanding chemical reaction mechanisms, particularly in reactions involving light atoms like hydrogen. However, recent findings have expanded this understanding to include heavy-atom tunneling reactions. In this report, we present the observation of two heavy-atom tunneling reactions involving the spontaneous conversions from end-on bonded beryllium ozonide complexes, OBeOOO () and BeOBeOOO (), to their corresponding side-on bonded ozonide isomers, OBe(η-O) () and BeOBe(η-O) (), respectively, in a cryogenic neon matrix. This discovery is supported by the weak temperature dependence of the rate constants and unusually large O/O kinetic isotope effects. Quantum chemistry calculations reveal extremely low barriers (<1 kcal/mol) for both ring-closure reactions. Additionally, instanton theory calculations on both reactions unveil that the tunneling processes involve the concerted motion of all four oxygen atoms.
长期以来，量子力学隧穿（QMT）一直被认为对于理解化学反应机制至关重要，尤其是在涉及氢等轻原子的反应中。然而，最近的研究结果将这一认识扩展到了重原子隧穿反应。在本报告中，我们展示了在低温氖基质中观察到的两个重原子隧穿反应，分别是从端基键合的铍臭氧化物配合物OBeOOO（）和BeOBeOOO（）自发转化为其相应的侧基键合臭氧化物异构体OBe(η - O)（）和BeOBe(η - O)（）。速率常数对温度的微弱依赖性以及异常大的O/O动力学同位素效应支持了这一发现。量子化学计算表明这两个闭环反应的势垒极低（<1千卡/摩尔）。此外，对这两个反应的瞬子理论计算揭示，隧穿过程涉及所有四个氧原子的协同运动。
