Barwa Erik, Ončák Milan, Pascher Tobias F, Taxer Thomas, van der Linde Christian, Beyer Martin K
Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Technikerstraße 25 , 6020 Innsbruck , Austria.
J Phys Chem A. 2019 Jan 10;123(1):73-81. doi: 10.1021/acs.jpca.8b10530. Epub 2018 Dec 19.
Hydrated singly charged metal ions doped with carbon dioxide, Mg(CO)(HO) , in the gas phase are valuable model systems for the electrochemical activation of CO. Here, we study these systems by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry combined with ab initio calculations. We show that the exchange reaction of CO with O proceeds fast with bare Mg(CO), with a rate coefficient k = 1.2 × 10 cm s, while hydrated species exhibit a lower rate in the range of k = (1.2-2.4) × 10 cm s for this strongly exothermic reaction. Water makes the exchange reaction more exothermic but, at the same time, considerably slower. The results are rationalized with a need for proper orientation of the reactants in the hydrated system, with formation of a Mg(CO)(HO) intermediate while the activation energy is negligible. According to our nanocalorimetric analysis, the exchange reaction of the hydrated ion is exothermic by -1.7 ± 0.5 eV, in agreement with quantum chemical calculations.
气相中掺杂二氧化碳的水合单电荷金属离子Mg(CO)(HO) 是用于CO电化学活化的重要模型体系。在此，我们通过傅里叶变换离子回旋共振（FT-ICR）质谱结合从头算计算来研究这些体系。我们表明，CO与O在裸露的Mg(CO)上的交换反应进行得很快，速率系数k = 1.2 × 10 cm s，而对于这个强放热反应，水合物种的反应速率较低，范围为k = (1.2 - 2.4) × 10 cm s。水使交换反应的放热更多，但同时反应速率大幅降低。通过水合体系中反应物需要适当取向、形成Mg(CO)(HO) 中间体且活化能可忽略不计来解释这些结果。根据我们的纳米量热分析，水合离子的交换反应放热为 -1.7 ± 0.5 eV，与量子化学计算结果一致。
