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化学学报
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化学学报 ›› 2010, Vol. 68 ›› Issue (07): 633-640. 上一篇    下一篇

研究论文

一种非血红素四氮杂轮烯配合物[Fe(III)TMTAA]催化过氧化氢歧化反应机理的理论研究

张颖1，王欣*,2，李来才*,1   

  1. (1四川师范大学化学与材料科学学院 成都 610066)
    (2四川大学化学学院 成都 610064)
  • 投稿日期:2009-04-27 修回日期:2009-08-20 发布日期:2010-04-14
  • 通讯作者: 李来才 E-mail:lilcmail@163.com

Theoretical Investigation on Reaction Mechanism of H2O2 Dismutation Catalyzed by a Non-heme Tetraaza Annulene Complex [Fe(III)TMTAA]

Zhang Ying1 Wang Xin*,2 Li Laicai*,1   

  1. (1 College of Chemistry and Material Science, Sichuan Normal University, Chengdu 610066)
    (2 Faculty of Chemistry, Sichuan University, Chengdu 610064)
  • Received:2009-04-27 Revised:2009-08-20 Published:2010-04-14

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采用密度泛函理论B3LYP方法计算了一种非血红素四氮杂轮烯配合物[Fe(III)TMTAA]催化H2O2歧化的反应机理. 对二重态、四重态和六重态势能面上各驻点进行了全优化, 发现反应易于沿四重态势能面发生. 整个反应分两阶段进行, 第一阶段通过氧氧均裂形成中间体IM6和第一个水, 第二阶段经两次氢转移形成第二个水. 反应决速步骤为 O—O均裂步骤, 能垒为63.9 kJ•mol－1, 相对于自由H2O2均裂所需能垒226.7 kJ•mol－1有较大的降低. 这表明标题配合物可有效地降低标题反应的能垒, 有可能作为一种潜在的过氧化氢仿酶.

关键词: 大环配合物, 四氮杂轮烯, 过氧化氢仿酶, 密度泛函理论, 反应机理, 中间体, 过渡态

The reaction mechanism of H2O2 dismutation catalyzed by a non-heme tetraaza annulene complex [Fe(III)TMTAA] has been investigated by density functional theory using the B3LYP functional. All the stationary points on the doublet, quartet, and sextet potential energy surfaces (PES) have been fully optimized. The reaction undergoes preferentially on the quartet PES. The whole reaction can be divided into two stages. In the stage 1, the complex is oxidized by H2O2 through an O—O bond homolytic cleavage pathway and the intermediate IM6 and the first H2O molecule are formed. In the stage 2, the IM6 is reduced by the second H2O2 molecule via two hydrogen abstraction steps and O2 and the second H2O are formed. The rate-determining step was found to be the O—O bond breaking step with a barrier of 63.9 kJ•mol－1. The calculated barrier for the O—O homolytic cleavage in dismutation of free H2O2 is 226.7 kJ•mol－1. The results indicate that the [Fe(III)TMTAA] complex can decrease energy barrier of the titled reaction and it may be a potential candidate for catalase mimic.

Key words: macrocyclic complex, tetraaza annulene, catalase mimic, density functional theory, reaction mechanism, intermediate, transition state