Piris Mario, Lopez Xabier, Ugalde Jesus M
Donostia International Physics Center (DIPC) & Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), 20018 Donostia, Euskadi, Spain.
Basque Foundation for Science (IKERBASQUE), 48009 Bilbao, Euskadi, Spain.
J Phys Chem Lett. 2024 Dec 12;15(49):12138-12143. doi: 10.1021/acs.jpclett.4c03010. Epub 2024 Nov 28.
Direct-dynamics simulations monitor atomic nuclei trajectories during chemical reactions, where chemical bonds are broken and new ones are formed. While they provide valuable information about the ongoing nuclear dynamics, the evolution of the chemical bonds is customarily overlooked, thus, hindering key information about the reaction mechanism. Here we examine the evolution of the chemical bonds for the three main mechanisms of the F + CHCHCl reaction using quasi-classical trajectories for the nuclei, and global natural orbitals for the electrons. Key findings include (i) bimolecular nucleophilic substitution (S2) resembles a one-step bond breaking and formation process; (ii) the elimination mechanisms (- and -E2) feature a sequential two-step process of proton abstraction and Cl elimination; and (iii) the -E2 mechanism is slower, exhibits rebound effects, and gets activated by specific vibrational modes. This study highlights the importance of correctly describing and thoroughly analyzing the dynamical evolution of chemical bonds for chemical reaction mechanistic studies.
直接动力学模拟监测化学反应过程中原子核的轨迹，在此过程中化学键断裂并形成新的化学键。虽然它们提供了有关正在进行的核动力学的有价值信息，但化学键的演化通常被忽视，因此阻碍了有关反应机理的关键信息。在这里，我们使用原子核的准经典轨迹和电子的全局自然轨道，研究了F + CHCHCl反应的三种主要机理中化学键的演化。主要发现包括：（i）双分子亲核取代（S2）类似于一步断键和形成过程；（ii）消除机理（-和-E2）具有质子夺取和Cl消除的顺序两步过程；（iii）-E2机理较慢，表现出反弹效应，并被特定的振动模式激活。这项研究强调了正确描述和全面分析化学键的动力学演化对于化学反应机理研究的重要性。
