Brüssel Marc, di Dio Philipp J, Muñiz Kilian, Kirchner Barbara
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, University Leipzig, Linnéstr. 2, D-04103 Leipzig, Germany; E-Mails:
Int J Mol Sci. 2011 Feb 23;12(2):1389-409. doi: 10.3390/ijms12021389.
We carried out ab initio molecular dynamic simulations in order to determine the free energy surfaces of two selected reactions including solvents, namely a rearrangement of a ruthenium oxoester in water and a carbon dioxide addition to a palladium complex in carbon dioxide. For the latter reaction we also investigated the gas phase reaction in order to take solvent effects into account. We used two techniques to reconstruct the free energy surfaces: thermodynamic integration and metadynamics. Furthermore, we gave a reasonable error estimation of the computed free energy surface. We calculated a reaction barrier of ΔF = 59.5 ± 8.5 kJ mol(-1) for the rearrangement of a ruthenium oxoester in water from thermodynamic integration. For the carbon dioxide addition to the palladium complex in carbon dioxide we found a ΔF = 44.9 ± 3.3 kJ mol(-1) from metadynamics simulations with one collective variable. The investigation of the same reactions in the gas phase resulted in ΔF = 24.9 ± 6.7 kJ mol(-1) from thermodynamic integration, in ΔF = 26.7 ± 2.3 kJ mol(-1) from metadynamics simulations with one collective variable, and in ΔF = 27.1 ± 5.9 kJ mol(-1) from metadynamics simulations with two collective variables.
我们进行了从头算分子动力学模拟，以确定两个选定反应（包括溶剂）的自由能面，即水中钌氧酯的重排反应以及二氧化碳中钯配合物与二氧化碳的加成反应。对于后一个反应，我们还研究了气相反应以考虑溶剂效应。我们使用了两种技术来重构自由能面：热力学积分和元动力学。此外，我们对计算得到的自由能面进行了合理的误差估计。通过热力学积分，我们计算出水中钌氧酯重排反应的反应势垒为ΔF = 59.5 ± 8.5 kJ mol⁻¹。对于二氧化碳中钯配合物与二氧化碳的加成反应，通过单集体变量的元动力学模拟，我们得到ΔF = 44.9 ± 3.3 kJ mol⁻¹。对气相中相同反应的研究表明，通过热力学积分得到ΔF = 24.9 ± 6.7 kJ mol⁻¹，通过单集体变量的元动力学模拟得到ΔF = 26.7 ± 2.3 kJ mol⁻¹，通过双集体变量的元动力学模拟得到ΔF = 27.1 ± 5.9 kJ mol⁻¹。
