Reaction path Hamiltonian analysis of dynamical solvent effects for a Claisen rearrangement and a Diels-Alder reaction
Reaction path Hamiltonian analysis of dynamical solvent effects for a Claisen rearrangement and a Diels-Alder reaction
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DOI：
10.1021/jp000449e
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发表时间：
2000-08-31
影响因子：
2.9
通讯作者：
Hammes-Schiffer, S
中科院分区：
文献类型：
--
作者：
Hu, H;Kobrak, MN;Hammes-Schiffer, S
研究了Claisen重排反应和Diels-Alder反应的溶剂效应。电子结构方法用于在气相和存在两个水分子的情况下产生这些反应的沿着最小能量路径的频率、耦合和曲率。的几何形状和电荷分布沿着最小能量路径进行了分析，以确定水分子的结构和静电作用。基于反应路径哈密顿量的反应通量分子动力学方法被用来计算动态传输系数，该系数考虑了过渡态的再交叉。克莱森重排的透射系数在气相和两个水分子存在下都接近于1。Diels-Alder反应的透射系数在气相和两个水分子存在下分别为0.95和0.89。透射系数的这些差异解释的曲率峰沿着的反应路径的位置和幅度，以及沿沿着的过渡态附近的反应坐标的势能的形状。动力学轨迹的分析提供了洞察水分子的动力学作用，并阐明了可能的反应机制。
The solvent effects for a Claisen rearrangement and a Diels-Alder reaction are investigated. Electronic structure methods are used to generate the frequencies, couplings, and curvatures along the minimum energy paths for these reactions in the gas phase and in the presence of two water molecules. The geometries and charge distributions along the minimum energy paths are analyzed to determine the structural and electrostatic roles of the water molecules. Reactive flux molecular dynamics methods based on a reaction path Hamiltonian are used to calculate the dynamical transmission coefficients, which account for recrossings of the transition state. The transmission coefficients for the Claisen rearrangement are nearly unity both in the gas phase and in the presence of two water molecules. The transmission coefficients for the Diels-Alder reaction are 0.95 and 0.89 in the gas phase and in the presence of two water molecules, respectively. These differences in the transmission coefficients are explained in terms of the locations and magnitudes of the curvature peaks along the reaction path, as well as the shape of the potential energy along the reaction coordinate near the transition state. Analysis of the dynamical trajectories provides insight into the dynamical role of the water molecules and elucidates possible reaction mechanisms.