第六配位基对S=2[Fe^(Ⅳ)(O)(TQA)(L)]^(n+)配合物反应活性的影响  

The effect of the sixth ligand on the reactivity of S=2[Fe^(Ⅳ)(O)(TQA)(L)]^(n+) complexes

作　　者：李清月 李文志 王禹茜 王一[1] 贺晓阳[2] LI Qingyue;LI Wenzhi;WANG Yuxi;WANG Yi;HE Xiaoyang(School of Biological Engineering, Dalian Polytechnic University, Dalian 116034, China;School of Information Science and Engineering, Dalian Polytechnic University, Dalian 116034, China)

机构地区：[1]大连工业大学生物工程学院,辽宁大连116034 [2]大连工业大学信息科学与工程学院,辽宁大连116034

出　　处：《大连工业大学学报》2021年第6期427-432,共6页Journal of Dalian Polytechnic University

基　　金：辽宁省自然科学基金项目(20180550765).

摘　　要：利用密度泛函理论研究了S=2的四价非血红素铁模型配合物[Fe^(Ⅳ)(O)(TQA)(L)]^(n+)(L=None,AN,OTf)的几何结构、电子结构以及羟基化和环氧化的反应机理。B3LYP计算结果表明,三种配合物的羟基化和环氧化都是单态反应,发生在五重态的反应势能面上。过渡态结构分析表明,羟基化与环氧化的反应机制与铁氧体系和底物之间的空间位阻效应有关,电子结构和空间位阻效应共同决定了反应能垒的高低。对比三个体系的反应能垒,环氧化速控步骤的平衡速度比羟基化反应速控步骤的速度要快,但是羟基化产物要比环氧化产物稳定。五配位[Fe^(Ⅳ)(O)(TQA)]^(2+)羟基化反应能垒低于两种六配位配合物,加上隧穿效应校正,三者的反应能垒一致,说明隧穿效应对六配位配合物的影响较大。[Fe^(Ⅳ)(O)(TQA)]^(2+)环氧化反应能垒高于[Fe^(Ⅳ)(O)(TQA)(AN)]^(2+)和[Fe^(Ⅳ)(O)(TQA)(OTf)]^(+)。The geometric and electronic structures,mechanisms of the hydroxylation and epoxidation reactions of the[Fe^(Ⅳ)(O)(TQA)(L)]^(n+)(L=None,AN,OTf)complexes with S=2 ground spin state have been calculated by the theory of density function.The results by calculation of B3LYP showed that the hydroxylation and epoxidation of these three complexes were singleton reactions,which occurred on the potential energy surface of quintet spin state.The structural analysis of transition states confirmed that the mechanisms the hydroxylation and epoxidation reactions were related to the steric hindrance between ferrite system and substrate,and the value of reaction energy barrier depended to the coefficient of steric hindrance and electronic structures.In comparison of the barriers of the three systems,the equilibrium speed of the epoxidation was faster than that of hydroxylation,whereas the product of hydroxylation was more stable than that of epoxidation.The reaction barrier of[Fe^(Ⅳ)(O)(TQA)]^(2+)was lower than that of the two hexa-coordinated complexes.After calibration by the tunneling effect,the reaction barriers of these three complexes were similar,indicating that the tunneling effect had great influence on reactivity of the hexa-coordinated complexes.The epoxidation reaction barrier of[Fe^(Ⅳ)(O)(TQA)]^(2+)was higher than that of[Fe^(Ⅳ)(O)(TQA)(OTf)]^(+).

关 键 词：非血红素铁 高自旋态 羟基化反应 环氧化反应 密度泛函理论 

分 类 号：O641[理学—物理化学]