A theoretical study on the oxidation of alkenes to aldehydes catalyzed by ruthenium porphyrins using O-2 as the sole oxidant
A theoretical study on the oxidation of alkenes to aldehydes catalyzed by ruthenium porphyrins using O-2 as the sole oxidant
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O-2为唯一氧化剂钌卟啉催化烯烃氧化制醛的理论研究
DOI：
10.1039/c8dt00614h
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发表时间：
2018
影响因子：
4
通讯作者：
Che Chi-Ming
中科院分区：
文献类型：
--
作者：
Zhang Lin-Lin;Wang Xiang-Yun;Jiang Kun-Yao;Zhao Bing-Yuan;Yan Hui-Min;Zhang Xiao-Yun;Zhang Zhu-Xia;Guo Zhen;Che Chi-Ming
采用密度泛函理论（DFT）方法研究了钌卟啉催化氧化苯乙烯生成醛的反应。结果表明，二氧钌和一氧钌-超氧卟啉两种活性氧化剂参与了催化氧化反应。在该机制中，生成的单氧钌卟啉在串联环氧化物异构化（E-I）中起作用，选择性地产生醛并生成二氧钌卟啉，从而引发新的氧化反应循环。在这个计算中，已经通过使用前线分子轨道（FMO）理论、自然键轨道（NBO）分析等建立了负责观察到的氧化能力的几个关键元素，包括反应能量、自旋交换效应、自旋态转换过程和反应性氧化剂的最低未占分子轨道（LUMO）能级。比较了不同轴向配体的鎓-氧代/超氧代化合物的氧化能力。结果表明，具有氯轴向配体的铼-氧代/超氧代物种比被氧取代的更具反应性。当考虑到两个配体的不同电子特征和有效原子序数规则（EAN）时，可以理解这种可调谐的反应性。
Density functional theory (DFT) calculations were used to study the ruthenium porphyrin-catalyzed oxidation of styrene to generate an aldehyde. The results indicate that two reactive oxidants, dioxoruthenium and monooxoruthenium-superoxo porphyrins, participate in the catalytic oxidation. In the mechanism, the resultant monooxoruthenium porphyrin acts in the tandem epoxide isomerization (E-I) to selectively yield an aldehyde and generate a dioxoruthenium porphyrin, thereby triggering new oxidation reaction cycles. In this calculation, several key elements responsible for the observed oxidative ability have been established by using Frontier molecular orbital (FMO) theory, natural bond orbital (NBO) analysis, etc., which include the reaction energy, the spin exchange effect, the spin-state conversion process, and the energy level of the lowest unoccupied molecular orbitals (LUMOs) of the reactive oxidants. The comparative oxidative abilities of the ruthenium-oxo/superoxo compounds with different axial ligands are also investigated. The results suggest that the ruthenium-oxo/superoxo species featuring a chlorine axial ligand is more reactive than that substituted with oxygen. This tuneable reactivity can be understood when considering the different electronic characters of the two ligands and the effective atomic number rule (EAN).