论文标题
竞争E2和S $ _ \ text {n} $ 2反应的数千个反应物和过渡状态
Thousands of reactants and transition states for competing E2 and S$_\text{N}$2 reactions
论文作者
论文摘要
反应屏障是基于第一原理的计算复古合成工作以及整个化学复合空间的全面反应性评估的关键成分。尽管存在实验结果的广泛数据库，但现代量子机学习应用程序需要原子细节，只能从量子化学方案中获得。对于竞争E2和S $ _ \ text {n} $ 2反应通道，我们报告了4'466过渡状态和143'200的143'200反应物复合物的几何形状和能量，以及各个MP2/6-311G（D）和单点DF-LCCSD/CC-LCCSD/CC-PVTZ的理论覆盖化学上的$ __2 NH $ _2 $和早期卤素（F，Cl，Br）作为亲核者和离开组。选择反应物使竞争E2和S $ _ \ text {n} $ 2反应的激活能量相当。对于所有过渡状态，已经验证了每个单步反应的正确协同运动。我们演示了量子机学习模型如何支持数据集扩展，并讨论过渡状态的关键内部坐标的分布。
Reaction barriers are a crucial ingredient for first principles based computational retro-synthesis efforts as well as for comprehensive reactivity assessments throughout chemical compound space. While extensive databases of experimental results exist, modern quantum machine learning applications require atomistic details which can only be obtained from quantum chemistry protocols. For competing E2 and S$_\text{N}$2 reaction channels we report 4'466 transition state and 143'200 reactant complex geometries and energies at respective MP2/6-311G(d) and single point DF-LCCSD/cc-pVTZ level of theory covering the chemical compound space spanned by the substituents NO$_2$, CN, CH$_3$, and NH$_2$ and early halogens (F, Cl, Br) as nucleophiles and leaving groups. Reactants are chosen such that the activation energy of the competing E2 and S$_\text{N}$2 reactions are of comparable magnitude. The correct concerted motion for each of the one-step reactions has been validated for all transition states. We demonstrate how quantum machine learning models can support data set extension, and discuss the distribution of key internal coordinates of the transition states.
