Pierloot Kristine, Phung Quan Manh, Ghosh Abhik
Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium.
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan.
Inorg Chem. 2020 Aug 17;59(16):11493-11502. doi: 10.1021/acs.inorgchem.0c01312. Epub 2020 Jul 27.
An elaborate study with multireference second-order perturbation theory has been performed to elucidate the electronic structure and relative energy of three relevant states of FeNO corroles, namely the = 0 ground state, the lowest = 1 state, and the anion = / state. On the basis of CASSCF and DMRG calculations with an active space including up to 37 orbitals, the electronic structure of the ground state was analyzed, with special emphasis on the diradical nature of the Fe-corrole and Fe-NO bonds. The results essentially confirm an earlier suggestion from B3LYP of a non-innocent corrole bound to an {FeNO} unit, although the contribution of diradical character to the iron-corrole bond is found to be limited to 35%. This limited diradical character explains the high relative energy (16.5 kcal/mol) of the corresponding triplet state, where the corrole is ferromagnetically coupled to the = / {FeNO} unit. Consistent with experimental findings, reduction is found to take place at the corrole ligand, with a calculated electron affinity of 52.5 kcal/mol. The results obtained from the correlated calculations were also compared to DFT with a broad range of functionals.
已进行了一项运用多参考二阶微扰理论的详尽研究，以阐明FeNO卟吩环三个相关态的电子结构和相对能量，即基态（(\Lambda = 0)）、最低的(\Lambda = 1)态以及阴离子态（(\Lambda = 1/2)）。基于包含多达37个轨道的活性空间进行的CASSCF和DMRG计算，分析了基态的电子结构，特别强调了Fe - 卟吩环和Fe - NO键的双自由基性质。结果基本证实了B3LYP早期提出的与{FeNO}单元结合的非无辜卟吩环的观点，尽管发现双自由基特征对铁 - 卟吩环键的贡献仅限于35%。这种有限的双自由基特征解释了相应三重态的高相对能量（16.5千卡/摩尔），其中卟吩环与(\Lambda = 1/2)的{FeNO}单元铁磁耦合。与实验结果一致，发现还原发生在卟吩环配体上，计算得到的电子亲和能为52.5千卡/摩尔。还将相关计算得到的结果与使用多种泛函的DFT结果进行了比较。
