Realistic modeling of ruthenium-catalyzed transfer hydrogenation
Realistic modeling of ruthenium-catalyzed transfer hydrogenation
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DOI：
10.1021/ja062359e
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发表时间：
2007-03-21
影响因子：
15
通讯作者：
Meijer, Evert Jan
中科院分区：
文献类型：
--
作者：
Handgraaf, Jan-Willem;Meijer, Evert Jan
我们报告的第一个计算研究的一个完全原子模型的铑催化转移氢化的甲醛和逆反应在一个明确的甲醇溶液。利用从头算分子动力学技术，我们确定了反应的热力学、反应机理和沿着的电子结构，为了定量评估溶剂的影响，我们与气相反应进行了直接比较。我们发现，在溶液中的能量分布在气相中的配置文件几乎没有相似之处，并发现了一个独特的溶剂化障碍：在两个方向上的活化势垒降低和协调的氢化物和质子转移在气相中被转换成一个连续的机制，在溶液中与基板出现的甲氧基中间体。我们的研究结果表明，除了金属配体双功能机制，如Noyori提出的，也是一个协调的溶剂介导的机制是可行的。我们的研究为溶剂在过渡金属催化反应中的积极作用提供了一个新的视角。
We report the first computational study of a fully atomistic model of the ruthenium-catalyzed transfer hydrogenation of formaldehyde and the reverse reaction in an explicit methanol solution. Using ab initio molecular dynamics techniques, we determined the thermodynamics, mechanism, and electronic structure along the reaction path. To assess the effect of the solvent quantitatively, we make a direct comparison with the gas-phase reaction. We find that the energy profile in solution bears little resemblance to the profile in the gas phase and a distinct solvation barrier is found: the activation barriers in both directions are lowered and the concerted hydride and proton transfer in the gas phase are converted into a sequential mechanism in solution with the substrate appearing as methoxide-like intermediate. Our results indicate that besides the metal-ligand bifunctional mechanism, as proposed by Noyori, also a concerted solvent-mediated mechanism is feasible. Our study gives a new perspective of the active role a solvent can have in transition-metal-catalyzed reactions.