轴联体对非血氧铁 (IV) 复合物的几何和电子结构的影响
Timothy A Jackson1, Jan-Uwe Rohde, Mi Sook Seo
1Department of Chemistry and Center for Metals in Biocatalysis, 207 Pleasant Street S.E., University of Minnesota, Minneapolis, Minnesota 55455, USA.
Journal of the American Chemical Society
|August 21, 2008
概括
这项研究合成了新型的oxoiron(IV) 复合物与不同的转基因连接物,揭示了这些连接物如何显著改变铁-oxo单元的光谱特征. 密度函数理论计算阐明了这些观察到的光谱变化背后的电子机制.
科学领域:
- 无机化学 无机化学
- 生物有机化学 生物有机化学
- 计算化学的计算化学
背景情况:
- 非血氧铁 (IV) 复合物是生物氧化反应中的关键中间体.
- 四甲基环 (TMC) 连接体为研究氧铁 (IV) 核的电子性质提供了一个稳定的支架.
- 了解轴联体对Fe=O键的影响是阐明反应机制的关键.
研究的目的:
- 合成和表征一系列S=1 oxoiron(IV) 复合体与不同的转接质体 (X).
- 为了研究这些转配体对Fe(IV) =O单元的光谱性质的影响.
- 通过计算方法阐明负责观察到的光谱变化的电子机制.
主要方法:
- 通过[Fe (IV) (O) (TMC) (NCMe) 2+) 与NR4X盐的反应合成[Fe (IV) (O) (TMC) (NCMe) 2+) 复合体.
- 使用电子吸收,Fe K边缘X射线吸收,共振拉曼和莫斯尔光谱学的表征.
- 使用密度函数理论 (DFT) 和时间依赖 DFT (TD-DFT) 的计算分析.
主要成果:
- 一系列S=1氧铁(IV) 复合物与不同的转配体 (X = OH(-),CF3CO2(-),N3(-),NCS(-),NCO(-),CN(-)) 已成功合成.
- 光谱特征 (近红外吸收,X射线吸收前边缘,莫斯尔四极分裂) 显示强烈依赖转接质体.
- Fe=O 键长度基本保持一致,而 DFT 揭示了 Fe=O 反键轨道的转配体调节.
结论:
- 变配体的身份显著影响S=1氧铁 (IV) 单元的电子结构和光谱特性.
- DFT计算准确地预测实验观测结果,并揭示控制这些变化的轨道相互作用.
- 给特定的配体分配了电荷转移过渡,解释了Fe=O模式的共振拉曼增强.
更多相关视频
11:04Ion Mobility-Mass Spectrometry Techniques for Determining the Structure and Mechanisms of Metal Ion Recognition and Redox Activity of Metal Binding Oligopeptides
Published on: September 7, 2019
13:21Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
Published on: July 21, 2011
相关概念视频
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:19Complexation Equilibria: The Chelate Effect
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...