Electronic Structure and Reactivity of Mononuclear Nonheme Iron–Peroxo Complexes as a Biomimetic Model of Rieske Oxygenases: Ring Size Effects of Macrocyclic Ligands,Journal of the American Chemical Society

当前位置： X-MOL 学术 › J. Am. Chem. Soc. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Electronic Structure and Reactivity of Mononuclear Nonheme Iron–Peroxo Complexes as a Biomimetic Model of Rieske Oxygenases: Ring Size Effects of Macrocyclic Ligands
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2023-12-26 , DOI: 10.1021/jacs.3c08559
Wenjuan Zhu ₁ , Peng Wu ₂ , Virginia A Larson ₃ , Akhilesh Kumar ₁ , Xiao-Xi Li _{1,

4} , Mi Sook Seo ₁ , Yong-Min Lee ₁ , Binju Wang ₅ , Nicolai Lehnert ₃ , Wonwoo Nam _{1,

6}

Affiliation

We report the macrocyclic ring size–electronic structure–electrophilic reactivity correlation of mononuclear nonheme iron(III)-peroxo complexes bearing N-tetramethylated cyclam analogues (n-TMC), [Fe^III(O₂)(12-TMC)]⁺ (1), [Fe^III(O₂)(13-TMC)]⁺ (2), and [Fe^III(O₂)(14-TMC)]⁺ (3), as a model study of Rieske oxygenases. The Fe(III)-peroxo complexes show the same δ and pseudo-σ bonds between iron and the peroxo ligand. However, the strength of these interactions varies depending on the ring size of the n-TMC ligands; the overall Fe–O bond strength and the strength of the Fe–O₂ δ bond increase gradually as the ring size of the n-TMC ligands becomes smaller, such as from 14-TMC to 13-TMC to 12-TMC. MCD spectroscopy plays a key role in assigning the characteristic low-energy δ → δ* LMCT band, which provides direct insight into the strength of the Fe–O₂ δ bond and which, in turn, is correlated with the superoxo character of the iron-peroxo group. In oxidation reactions, reactivities of 1–3 toward hydrocarbon C–H bond activation are compared, revealing the reactivity order of 1 > 2 > 3; the [Fe^III(O₂)(n-TMC)]⁺ complex with a smaller n-TMC ring size, 12-TMC, is much more reactive than that with a larger n-TMC ring size, 14-TMC. DFT analysis shows that the Fe(III)-peroxo complex is not reactive toward C–H bonds, but it is the end-on Fe(II)-superoxo valence tautomer that is responsible for the observed reactivity. The hydrogen atom abstraction (HAA) reactivity of these intermediates is correlated with the overall donicity of the n-TMC ligand, which modulates the energy of the singly occupied π* superoxo frontier orbital that serves as the electron acceptor in the HAA reaction. The implications of these results for the mechanism of Rieske oxygenases are further discussed.

中文翻译：

作为 Rieske 氧化酶仿生模型的单核非血红素铁过氧配合物的电子结构和反应性：大环配体的环尺寸效应

我们报道了带有N -四甲基化仙客来类似物 ( n -TMC)、[Fe ^III (O ₂ )(12-TMC)] ⁺ ( 1 )、[Fe ^III (O ₂ )(13-TMC)] ⁺ ( 2 ) 和 [Fe ^III (O ₂ )(14-TMC)] ⁺ ( 3 )，作为 Rieske 加氧酶的模型研究。 Fe(III)-过氧配合物在铁和过氧配体之间显示出相同的 δ 和伪 σ 键。然而，这些相互作用的强度根据n -TMC 配体的环大小而变化；随着n -TMC配体的环尺寸变小，例如从14-TMC到13-TMC再到12-TMC，总体Fe-O键强度和Fe-O ₂ δ键的强度逐渐增加。 MCD 光谱在分配特征低能 δ → δ* LMCT 能带方面发挥着关键作用，它可以直接洞察 Fe-O ₂ δ 键的强度，进而与铁的超氧特性相关-过氧化基团。在氧化反应中，比较1 – 3对烃C-H键活化的反应性，揭示反应性顺序为1 > 2 > 3 ；具有较小n -TMC 环尺寸的 [Fe ^III (O ₂ )( n -TMC)] ⁺络合物 12-TMC 比具有较大n -TMC 环尺寸的络合物 14-TMC 更具反应性。 DFT 分析表明，Fe(III)-过氧配合物对 C-H 键不具有反应性，但末端 Fe(II)-超氧价互变异构体是造成观察到的反应性的原因。这些中间体的氢原子夺取 (HAA) 反应性与n -TMC 配体的整体单性相关，后者调节单占据 π* 超氧前沿轨道的能量，该轨道在 HAA 反应中充当电子受体。进一步讨论了这些结果对 Rieske 加氧酶机制的影响。

更新日期：2023-12-26

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南