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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 k J·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(π*sub),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。
The density functional theory (DFT-B3LYP) was used to investigate the mechanism of non-heme iron-activated superoxide-activated propylene molecular polymorphism. The results show that the hydrogen abstraction process abides by the singlet reaction mechanism, With a lower activation energy (ΔG ~ ≠ = 65.6 kJ · mol -1), non-heme iron superoxide can be extracted as an effective oxidant hydrogen atoms. The monomorphic response mechanism may be due to the recently proposed exchange-enhanced reaction principle (EER, iron center has greater exchange stability). For the activation of the OO bond, the spin of the high spin (S1) and the quintet (Q0) in the cross section of the potential energy plane at CASSCF (10,8) / 6-31 + G (d) - orbital coupling (SOC) constants of 2.26 and 2.19 cm -1, respectively. The orbital analysis shows that the two spin-orbitals have the same space composition (π * sub) and the SOC is forbidden. Therefore, it is impossible to effectively cross the intersystem of quaternary (S = 3) State (S = 2) potential surface, the inter-system crossing may occur in the final exit of the reaction.