| 非血红素铁超氧化物活化丙烯分子多态反应机理的理论研究 |
| Theoretical Investigation on the Multi-State Reaction Mechanism for the Propene Catalyzed by Non-Heme Ferric-Superoxo Species |
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| 摘要: 采用密度泛函DFT-B3LYP理论对非血红素铁超氧化物活化丙烯分子多态反应机理进行了探讨. 研究结果表明氢原子抽取过程遵守单态反应机制，主要在基态高自旋七重态势能面进行，且具有较低活化能（ΔG≠=65.6 kJ·mol-1），非血红素铁超氧化物可以作为有效氧化剂抽取氢原子。单态反应机制可能归因于近来建议的交换-加强反应原则（EER，铁中心具有较大交换稳定作用）。对于O-O键的活化，在CASSCF（10，8）/6-31+G（d）//TZVP水平下，势能面交叉区内，高自旋七重态（S1）和五重态（Q0）的自旋-轨道耦合（SOC）常数分别为2.26和2.19 cm-1。轨道分析表明两条发生翻转自旋轨道具有相同空间组成（πsub*），SOC禁阻，因此通过SOC作用反应体系不可能有效地从七重态（S=3）势能面系间穿越到五重态（S=2）势能面，系间穿越可能发生在反应最后的退出阶段。 |
| 关键词: 非血红素铁超氧化物 多态反应机理 系间窜越 自旋轨道耦合 |
| 基金项目: 国家自然基金（No.21263022；21663025；2163024）、甘肃省教育厅导师基金和天水师范学院“青蓝”人才工程基金资助项目。 |
| Abstract: The multi-state reaction mechanism for the propene catalyzed by non-heme ferric-superoxo model complex has been investigated at the DFT-B3LYP level. The calculations show that non-heme ferric-superoxo complex can be considered as effective oxidants in hydrogen atom abstraction reaction (single-state-reactivity), for which we find a lower barrier of ΔG≠=65.6 kJ·mol-1 on the septet spin state surface. Single-state-reactivity is possibly due to the recently proposed exchange-enhanced reactivity (EER)principle with larger exchange stabilization of the Fe center. For the O-O bond activated step, we computed the spin-orbit coupling (SOC)constants of the septet, S1 and quintet, Q0 state at the crossing region and found it to be 2.26 and 2.19 cm-1 at the CASSCF (10, 8)/6-31+G (d)//TZVP levels, respectively. Orbital analysis show that two spin orbitals have the same spatial component in their wave functions (πsub*), therefore, the S=3 surface cannot effectively intersystem cross to the S=2 surface through the SOC interactions,and the intersystem crossing is possibly occurred at the exit stage of the reaction. |
| Keywords: non-heme ferric-superoxo multi-state reaction mechanism intersystem crossing spin-orbit coupling |
| 投稿时间：2016-02-04 修订日期：2016-12-03 |
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| 吕玲玲,朱元成,左国防,袁焜,王永成.非血红素铁超氧化物活化丙烯分子多态反应机理的理论研究[J].无机化学学报,2017,33(2):329-339. |
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