Hydrogen peroxide (H₂O₂), as clean oxidant, has been disregarded due to its low efficiency and selectivity for the oxidation of olefins. In the present paper, the redox‐important ferrate anion (FeO₄²⁻) has been anchored to a silanol‐decorated polyoxometalates (POM) to form a single site‐supported Fe‐POM catalyst. Possible reaction mechanisms for the epoxidation of propylene with H₂O₂ catalyzed by the Fe‐POM catalyst have been investigated based on density functional theory with the M06L functional. The study of molecular geometry, electronic structure, and bonding feature shows that the Fe‐POM complex can be viewed as a high‐valent Fe‐oxo (FeO) species. The propylene molecule was activated by the Fe‐POM catalyst via an effective electron transfer from propylene to the Fe‐POM catalyst to form a cation propylene radical. Due to the high reactivity of radical species, the calculated activation energy barrier is only 4.50 kcal mol⁻¹ for epoxidation of propylene to epoxypropane catalyzed by the Fe‐POM catalyst. Subsequently, the calculated free energy profiles show that H₂O₂ was decomposed into a H₂O molecule and a surface O species over the Fe‐POM catalyst, and the remaining O atom attaches to the exposed Fe center, resulting in the replenishing of the Fe‐POM catalyst via a two‐state reaction pathway. The calculated activation energy barrier for this process is 23.42 kcal mol⁻¹, and thus, decomposition of H₂O₂ is the rate‐determining step for the whole reaction. The Fe center serves as an electron acceptor, accepting electrons from the binding propylene molecule to form radical species in the first half of the reaction and, in the role of electron donor in the remaining reaction steps to eliminate the radical feature, reduces the reactivity and stops the reaction at the stage of the desired epoxypropane product.

中文翻译：

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硅烷醇官能化的多金属氧酸盐负载的高铁酸盐催化的过氧化氢对丙烯的环氧化作用：电子结构，键合特征和反应机理

作为清洁氧化剂的过氧化氢（H ₂ O ₂）由于其低效率和对烯烃氧化的选择性而被忽略。在本文中，重要的氧化还原高铁酸盐阴离子（FeO ₄ ^2-）被固定在硅烷醇修饰的多金属氧酸盐（POM）上，形成了单点负载的Fe-POM催化剂。丙烯与H ₂ O ₂环氧化的可能反应机理根据具有M06L官能度的密度泛函理论研究了Fe-POM催化剂催化的Fe。对分子几何结构，电子结构和键合特征的研究表明，Fe-POM配合物可以被视为高价的Fe-oxo（FeO）物种。Fe-POM催化剂通过从丙烯到Fe-POM催化剂的有效电子转移将丙烯分子活化，从而形成阳离子丙烯自由基。由于自由基的高反应活性，对于Fe-POM催化剂催化的丙烯环氧化为环氧丙烷，计算得出的活化能垒仅为4.50 kcal mol ^-1。随后，计算出的自由能分布表明，H ₂ O ₂被分解为H _2。Fe-POM催化剂上的O分子和表面O物种，剩余的O原子附着在暴露的Fe中心，导致Fe-POM催化剂通过两态反应途径进行补充。计算出的该过程的活化能垒为23.42 kcal mol ^-1，因此H ₂ O _2的分解是整个反应的决定速率的步骤。Fe中心用作电子受体，在反应的前半部分接受来自结合的丙烯分子的电子以形成自由基，并且在其余反应步骤中电子给体的作用中，其消除自由基的特性降低了反应性并在所需的环氧丙烷产物阶段停止反应。