一种高价值的铁氧科罗拉通过原子转移激活C-H键
Kevin Cho1, Pannee Leeladee, Amanda J McGown
1Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.
Journal of the American Chemical Society
|April 12, 2012
概括
研究人员合成了一种高价值的铁氧复合物,能够通过原子转移氧化C-H键. 阐明了反应机制和动力学,提供了对血红素类似物反应性的见解.
科学领域:
- 生物有机化学 生物有机化学
- 有机金属化学 有机金属化学
- 反应机制研究 反应机制研究
背景情况:
- 高价值的铁氧物种是各种酶反应中的关键中间体.
- 了解合成类型的反应性,可以深入了解生物系统.
- 合金酸联体为金属中心提供了独特的电子和硬质环境.
研究的目的:
- 为了合成和表征一种新的高价值铁氧复合体.
- 为了研究这种复杂的C-H键氧化的机制.
- 阐明控制这些氧化反应的反应性和选择性的因素.
主要方法:
- 使用O原子转移试剂氧化Fe(III) 冠酸盐复合物.
- 使用X射线吸收光谱学 (XAS) 进行高价值Fe(IV) = O复合物的表征.
- 动态研究,包括产品分析,激活参数的确定和动态同位素效应 (KIE).
主要成果:
- 一个反应性高价值Fe(IV) = O复合体, (TBP(8)Cz(+•))Fe(IV) ((O),已成功合成.
- XAS证实了具有短Fe-O键长 (1.64 Å) 的溶液结构.
- 氧化C-H是通过决定速度的原子转移 (HAT) 进行的,与C-H键解离能 (BDE) 相对应.
- 确定了氧化时的动力参数 (ΔH++, ΔS++, KIE) 和温度依赖的选择性 (氧化与二元化).
结论:
- 合成的高价值铁氧复合体是一种有能力的C-H氧化催化剂.
- 原子转移是观察到的C-H氧化反应中决定速度的步骤.
- 这项研究提供了关于化合物I海姆类型的内在反应性和选择性的宝贵见解.
相关概念视频
Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
Oxidation-Reduction Reactions
Oxidation–Reduction Reactions
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
Metal-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...

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