四苯基铁卟啉双氧加合物的密度泛函理论研究  

A DFT Investigation on the Dioxygen Adduct of Iron Tetraphenylporphyrin

作　　者：魏璐[1] 佘远斌[1] 于艳敏[1] 曹梅娟[1] 姚晓倩[2] 

机构地区：[1]北京工业大学环境与能源工程学院绿色化学与精细化工研究所,北京100124 [2]中国科学院过程工程研究所多相复杂系统国家重点实验室,北京100190

出　　处：《科学技术与工程》2012年第22期5419-5423,5428,共6页Science Technology and Engineering

基　　金：国家自然科学基金重点项目(21036009);北京市学术创新团队计划(PHR201107104);国家自然科学基金青年基金项目(20903007)资助

摘　　要：采用密度泛函理论方法计算了自旋多重度为1、3、5的四苯基铁卟啉双氧加合物(FeTPPO2)的几何构型及电子性质。考察了四苯基铁卟啉对分子氧的活化。研究发现,FeTPPO2能量随自旋多重度升高而降低。五重态FeTPPO2的能量最低,但其铁卟啉对分子氧的活化效果最差。FeTPPO2中Oa—Ob键键长随自旋多重度变化的规律为三重态>单重态>五重态,说明三重态FeTPPO2中分子氧活化最明显。Fe—Oa键键长和Oa—Ob键键长呈负相关关系。电荷布居分析表明,FeTPPO2中分子氧活化程度与分子氧上所带负电荷多少有关,所带负电荷越多,分子氧活化越明显。分析自旋密度得知,三重态FeTPPO2中分子氧为单线态分子氧。三重态和五重态FeTPPO2中,铁离子均向分子氧转移了β电子,有利于铁氧键的形成。The singlet, triplet and quintet dioxygen adduets of the iron tetraphenylporphyrin （FeTPPO2） were investigated at B3LYP/6-31 G^＊ level using Gaussian09 program package without any symmetry constraint. It is found that the total energy of FeTPPO2 is reduced with the spin multiplicity increasing. The iron tetraphenylporphytin in the quintet FeTPPO2 has little effect on activating dioxygen, although the quintet is the most stable spin state for FeTPPO2. The Fe--Oabond length in FeTPPO2 is changed in the sequence of the triplet 〈 the singlet 〈 the quintet, while the Q--Obbond length in FeTPPOz is changed in the totally opposite sequence of the triplet 〉 the singlet 〉 the quintet. It is shown that the activation of dioxygen in the triplet FeTPPO2 is most significant. There is a negative correlation between the Fe-Oa bond length and Oa-Ob bond length caused by the feedback bond from Fe 3d orbitals to the dioxygen of π^ ＊ orbital and the ionic bond between Fe and O a. Charge population analysis reveals that the dioxygen in FeTPPO2 always carries negative charges owing to the feedback bond from Fe 3d orbitals to the dioxygen of π^ ＊ orbital. The activation of dioxygen in FeTPPO2 has to do with the negative charge carried by dioxygen, that is, the more negative charges dioxygen bears, the more significant the activation of dioxygen is. According to the spin density, the dioxygen in the triplet FeTPPO2 is in an excited singlet, so the triplet FeTPPO2 may be more chemically active than the quintet FeTPPO2. electrons are transferred to the dioxygen from the central iron ion in both triplet and quintet FeTPPO2, which is favorable for the formation of Fe--Oa bond.

关 键 词：四苯基铁卟啉 双氧加合物 密度泛函理论 几何性质 电子性质 

分 类 号：O621.13[理学—有机化学]