Espinosa-Garcia Joaquin, Rangel Cipriano, Corchado Jose C
Departamento de Química Física and Instituto de Computación Científica Avanzada, Universidad de Extremadura, 06071 Badajoz, Spain.
Molecules. 2022 Jun 11;27(12):3773. doi: 10.3390/molecules27123773.
This paper is a detailed review of the chemistry of medium-size reactive systems using the following hydrogen abstraction reactions with ethane, X + CH → HX + CH; X ≡ H, F(P), Cl(P), O(P) and OH, and focusing attention mainly on the theoretical developments. These bimolecular reactions range from exothermic to endothermic systems and from barrierless to high classical barriers of activation. Thus, the topography of the reactive systems changes from reaction to reaction with the presence or not of stabilized intermediate complexes in the entrance and exit channels. The review begins with some reflections on the inherent problems in the theory/experiment comparison. When one compares kinetics or dynamics theoretical results with experimental measures, one is testing both the potential energy surface describing the nuclei motion and the kinetics or dynamics method used. Discrepancies in the comparison may be due to inaccuracies of the surface, limitations of the kinetics or dynamics methods, and experimental uncertainties that also cannot be ruled out. The paper continues with a detailed review of some bimolecular reactions with ethane, beginning with the reactions with hydrogen atoms. The reactions with halogens present a challenge owing to the presence of stabilized intermediate complexes in the entrance and exit channels and the influence of the spin-orbit states on reactivity. Reactions with O(P) atoms lead to three surfaces, which is an additional difficulty in the theoretical study. Finally, the reactions with the hydroxyl radical correspond to a reactive system with ten atoms and twenty-four degrees of freedom. Throughout this review, different strategies in the development of analytical potential energy surfaces describing these bimolecular reactions have been critically analyzed, showing their advantages and limitations. These surfaces are fitted to a large number of ab initio calculations, and we found that a huge number of calculations leads to accurate surfaces, but this information does not guarantee that the kinetics and dynamics results match the experimental measurements.
本文是对中等大小反应体系化学的详细综述，采用以下与乙烷的氢提取反应：X + CH → HX + CH；X ≡ H、F(P)、Cl(P)、O(P)和OH，并主要关注理论进展。这些双分子反应涵盖从放热到吸热体系，以及从无势垒到高经典活化势垒的情况。因此，反应体系的拓扑结构因反应而异，取决于入口和出口通道中是否存在稳定的中间复合物。综述首先对理论/实验比较中的固有问题进行了一些思考。当将动力学或动力学理论结果与实验测量进行比较时，实际上是在测试描述核运动的势能面以及所使用的动力学或动力学方法。比较中的差异可能源于表面的不准确、动力学或动力学方法的局限性，以及同样无法排除的实验不确定性。本文接着详细综述了一些与乙烷的双分子反应，首先是与氢原子的反应。与卤素的反应具有挑战性，因为入口和出口通道中存在稳定的中间复合物以及自旋 - 轨道状态对反应性的影响。与O(P)原子的反应导致三个势能面，这在理论研究中是一个额外的困难。最后，与羟基自由基的反应对应于一个具有十个原子和二十四个自由度的反应体系。在整个综述过程中，对描述这些双分子反应的解析势能面发展中的不同策略进行了批判性分析，展示了它们的优点和局限性。这些势能面与大量的从头算计算结果相拟合，我们发现大量的计算能得到准确的势能面，但这些信息并不能保证动力学和动力学结果与实验测量相匹配。
