Benchmark Study on Methanol C鈥揌 and O鈥揌 Bond Activation by Bare [FeIVO]2+
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- 作者：Xianhui Sun ; Xiaoli Sun ; Caiyun Geng ; Haitao Zhao ; Jilai Li
- 刊名：Journal of Physical Chemistry A
- 出版年：2014
- 出版时间：August 28, 2014
- 年：2014
- 卷：118
- 期：34
- 页码：7146-7158
- 全文大小：603K
- ISSN：1520-5215
文摘
We present a high-level computational study on methanol C鈥揌 and O鈥揌 bond cleavages by bare [FeIVO]2+, as well as benchmarks of various density functional theory (DFT) methods. We considered direct and concerted hydrogen transfer (DHT and CHT) pathways, respectively. The potential energy surfaces were constructed at the CCSD(T)/def2-TZVPP//B3LYP/def2-TZVP level of theory. Mechanistically, (1) the C鈥揌 bond cleavage is dominant and the O鈥揌 activation only plays minor role on the PESs; (2) the DHT from methyl should be the most practical channel; and (3) electronic structure analysis demonstrates the proton and electron transfer coupling behavior along the reaction coordinates. The solvent effect is evident and plays distinct roles in regulating the two bond activations in different mechanisms during the catalysis. The effect of optimizing the geometries using different density functionals was also studied, showing that it is not meaningful to discuss which DFT method could give the accurate prediction of the geometries, especially for transition structures. Furthermore, the gold-standard CCSD(T) method was used to benchmark 19 different density functionals with different Hartree鈥揊ock exchange fractions. The results revealed that (i) the structural factor plays a minor role in the single point energy (SPE) calculations; (ii) reaction energy prediction is quite challenging for DFT methods; (iii) the mean absolute deviations (MADs) reflect the problematic description of the DFs when dealing with metal oxidation state change, giving a strong correlation on the HF exchange in the DFs. Knowledge from this study should be of great value for computational chemistry, especially for the de novo design of transition metal catalysts.