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arXiv 1606.00580physics.chem-ph
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CO2与过渡金属-苯配合物结合的空间效应:第一性原理研究

Steric effects of CO2 binding to transition metal-benzene complexes: a first-principles study

Hyeonhu Bae, Bing Huang, Hoonkyung Lee

摘要:

采用密度泛函理论(DFT)方法研究了CO2分子在3d过渡金属(TM)-苯配合物上的吸附.我们的计算表明,最大的二氧化碳分子吸附在Sc或Ti原子的数目是3,但18电子规则预测它应该是4。18-电子规则在预测TM原子(包括Sc或Ti原子)的最大H2吸附数方面通常是成功的。我们发现,18-电子规则不能正确预测的Sc-或Ti-苯配合物上的CO2结合,因为CO2的结合,在相反的H2结合,需要额外的考虑空间位阻由于大键长的CO2。我们计算了使用托尔曼锥角,这表明,三个CO2分子完全占据了Sc-和Ti-苯配合物周围的可用空间的CO2的占领功能。该估计值与DFT计算预测的最大CO2吸附数相同。因此,我们建议使用托尔曼锥角的CO2占据函数是一个有效的模型,用于评估CO2吸附在表面上的空间位阻。

英文摘要:

Using density functional theory (DFT) calculations, we investigated the adsorption of CO2 molecules on 3d transition metal (TM)-benzene complexes. Our calculations show that the maximum number of CO2 molecules adsorbable on Sc or Ti atoms is three, but the 18-electron rule predicts it should be four. The 18-electron rule is generally successful in predicting the maximum H2 adsorption number for TM atoms including Sc or Ti atoms. We found that the 18-electron rule fails to correctly predict CO2 binding on Sc- or Ti-benzene complexes because CO2 binding, in contrast to H2 binding, requires additional consideration for steric hindrance due to the large bond length of CO2. We calculated the occupation function for CO2 using the Tolman cone angle, which shows that three CO2 molecules fully occupy the available space around Sc- and Ti-benzene complexes. This estimation is the same maximum CO2 adsorption number predicted by DFT calculations. Therefore, we propose that the occupation function for CO2 using the Tolman cone angle is an efficient model for evaluating steric hindrance of CO2 adsorption on a surface.

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