Bai Yuyao, Fu Yan-Lin, Qi Jianjun, Liu Lijie, Lu Xiaoxiao, Han Yong-Chang, Zhang Dong H, Fu Bina
School of Physics, Dalian University of Technology, Dalian, China.
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
Nat Commun. 2025 Mar 19;16(1):2732. doi: 10.1038/s41467-025-58121-w.
The conventional understanding of bimolecular reactions, which either proceed directly via well-defined transition states or pass through potential energy wells, is well-established. However, increasing attention and interest have been drawn to nontraditional reaction pathways, such as roaming mechanisms. Here, full-dimensional dynamics simulations on a machine learning-based potential energy surface reveal that the Cl + CH→CH+HCl reaction is dominated by two roaming mechanisms-Cl-roaming and H-roaming-rather than direct abstraction. In Cl-roaming, a transient CHCl adduct forms, allowing Cl to roam and abstract H. In H-roaming, a detached H atom migrates and abstracts Cl. These pathways account for nearly 100% of the total yield, exhibiting distinct energy and angular distributions. These findings challenge the traditional view of the bimolecular reaction with conventional transition states, emphasizing the importance of considering nontraditional pathways in reaction dynamics studies for accurate rate constant predictions and mechanistic insights.
双分子反应的传统理解是，其要么直接通过明确的过渡态进行，要么穿过势能阱，这种理解已得到充分确立。然而，非传统反应途径，如漫游机制，已引起越来越多的关注和兴趣。在此，基于机器学习势能面的全维动力学模拟表明，Cl + CH→CH+HCl反应主要由两种漫游机制——Cl-漫游和H-漫游——主导，而非直接提取。在Cl-漫游中，形成一个瞬态CHCl加合物，使Cl能够漫游并提取H。在H-漫游中，一个分离的H原子迁移并提取Cl。这些途径占总产量的近100%，呈现出独特的能量和角度分布。这些发现挑战了具有传统过渡态的双分子反应的传统观点，强调了在反应动力学研究中考虑非传统途径对于准确预测速率常数和获得机理见解的重要性。
