Dr. K. C. Patel R & D Centre, Charotar University of Science and Technology (CHARUSAT), 388421 Anand, Gujarat, India.
Department of Chemistry, Oakland University, Rochester, MI 48309-4477, USA.
J Inorg Biochem. 2025 Jan;262:112718. doi: 10.1016/j.jinorgbio.2024.112718. Epub 2024 Aug 30.
In this article, we report sterically-controlled iron sites based on non-chelating bulky imidazole ligands. Adding 6 equiv. of 1,2-dimethylimidazole (1,2-MeIm) to Fe(OTf)⋅2CHCN affords the first example of a 5-coordinate imidazole‑iron complex (Fe(1,2-MeIm), 1). The structure is distorted square pyramidal (τ = 0.41). When an Pr group is substituted for the methyl group at the 2-position on the imidazole (2-Pr-1-MeIm), the 14-electron complex (Fe(2-Pr-1-MeIm), 2) is obtained. This complex exhibits slightly distorted tetrahedral geometry (τ' = 0.93) with four N-donors and serves as a 4-His iron structural model complex for carotenoid cleavage dioxygenases (CCD). The electronic structure of 1 and 2 were characterized by Mössbauer spectroscopy. Reactions of 1 and 2 with model olefin substrates (1-R-4-(1-methoxyprop-1-en-2-yl)benzene; R = Me or Br) in the presence of oxygen result in olefin cleavage yielding ketone and aldehyde products, although 2 yields more products than 1. Support for a proposed reaction mechanism for 2 is offered from Density Functional Theory (DFT) calculations.
在本文中，我们报告了基于非螯合大位阻咪唑配体的立体控制的铁位点。向 Fe(OTf)⋅2CHCN 中加入 6 当量的 1,2-二甲基咪唑（1,2-MeIm），得到了第一个 5 配位咪唑-铁配合物(Fe(1,2-MeIm)，1)的实例。该结构为扭曲的四方锥（τ=0.41）。当咪唑的 2-位上的甲基被异丙基取代时（2-Pr-1-MeIm），得到 14 电子配合物(Fe(2-Pr-1-MeIm)，2)。该配合物呈现出略微扭曲的四面体几何形状（τ'=0.93），具有四个 N 供体，可作为类胡萝卜素裂解双加氧酶（CCD）的 4-His 铁结构模型配合物。1 和 2 的电子结构通过 Mössbauer 光谱进行了表征。1 和 2 与模型烯烃底物（1-R-4-(1-甲氧基丙-1-烯-2-基)苯；R=Me 或 Br）在氧气存在下反应导致烯烃裂解，生成酮和醛产物，尽管 2 的产物比 1 多。密度泛函理论（DFT）计算为 2 的提议反应机制提供了支持。
