Van't Hoff Institute for Molecular Sciences, Amsterdam Center for Multiscale Modeling, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
Faraday Discuss. 2019 Dec 2;220(0):404-413. doi: 10.1039/c9fd00055k.
In this work, we use density functional theory based molecular dynamics with an explicit description of methanol solvent to study the effect of cations on formic acid dehydrogenation catalyzed by a ruthenium PNP pincer complex (RuPNP). Formic acid dehydrogenation is a two step process that involves the reorientation of the formate moiety bound via its oxygen to a H bound intermediate, followed by the hydride transfer step to form CO2 and the hydrogenated catalyst. We find the reorientation step to proceed with a low barrier in methanol solvent and in the presence of a Li+ cation, while the hydride transfer is significantly hindered by the presence of cations (Li+ and K+). The cation seems to strongly stabilize the negatively charged formate moiety, hindering complete hydride transfer and resulting in a high barrier for this step. This study is a first step towards addressing the exact role of cations in formic acid dehydrogenation reactions.
在这项工作中，我们使用基于密度泛函理论的分子动力学方法，并采用甲醇溶剂的显式描述，研究阳离子对钌 PNP 钳形配合物（RuPNP）催化甲酸脱氢反应的影响。甲酸脱氢是一个分两步进行的过程，涉及通过其氧与 H 键合中间体结合的甲酸盐部分的重定向，然后进行氢化物转移步骤以形成 CO2 和加氢催化剂。我们发现，在甲醇溶剂中并存在 Li+阳离子的情况下，重定向步骤以低能垒进行，而氢化物转移则受到阳离子（Li+和 K+）的显著阻碍。阳离子似乎强烈稳定带负电荷的甲酸盐部分，阻碍完全的氢化物转移，并导致该步骤的能垒升高。这项研究是朝着确定阳离子在甲酸脱氢反应中的确切作用迈出的第一步。
