McIsaac Alexandra R, Mazziotti David A
Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, IL 60637, USA.
Phys Chem Chem Phys. 2017 Feb 8;19(6):4656-4660. doi: 10.1039/c6cp07563k.
We examine the 1-electron reduction of manganese porphyrin complexes Mn(iii) porphyrin and Mn(iii) TDE-2-ImP, which have attracted recent interest due to their properties as superoxide dismutase mimics. We perform a series of electronic structure calculations using the variational 2-electron reduced density matrix (2-RDM) method with a large [30,30] active space that represents a wavefunction with 10 variables, as well as the more traditional complete active space self-consistent field (CASSCF) method with a [14,14] active space. We show that the larger 2-RDM calculation, intractable with CASSCF, is required to capture the full effects of electron correlation in the molecule and predict the non-innocence of the porphyrin ligand during the reduction. The CASSCF method predicts single-reference systems exhibiting a metal-centered reduction, but the 2-RDM method predicts a strongly correlated system exhibiting a ligand-centered reduction. Based on these results, we find that the porphyrin ligand is reduced rather than the manganese, and suggest that the electron correlation plays a role in driving the ligand non-innocence.
我们研究了锰卟啉配合物Mn(III)卟啉和Mn(III) TDE - 2 - ImP的单电子还原反应，由于它们作为超氧化物歧化酶模拟物的性质，最近受到了关注。我们使用变分双电子约化密度矩阵（2 - RDM）方法进行了一系列电子结构计算，该方法采用了一个大的[30,30]活性空间，该空间代表一个具有10个变量的波函数，同时还使用了更传统的具有[14,14]活性空间的完全活性空间自洽场（CASSCF）方法。我们表明，更大的2 - RDM计算（CASSCF难以处理）对于捕捉分子中电子关联的全部效应以及预测还原过程中卟啉配体的非无辜性是必要的。CASSCF方法预测单参考体系表现出以金属为中心的还原，但2 - RDM方法预测一个强关联体系表现出以配体为中心的还原。基于这些结果，我们发现卟啉配体被还原而不是锰，并表明电子关联在驱动配体非无辜性方面起作用。
