甲基甲基酸盐的机制和过渡状态结构是双重协调到双核 (III) 中心的阿里尔甲基酸盐
Guoqiang Feng1, Eric A Tanifum, Harry Adams
1University of Sheffield, Centre for Chemical Biology, Department of Chemistry, Sheffield, UK S3 7HF.
Journal of the American Chemical Society
|August 14, 2009
概括
这项研究研究了二核 (III) 复合物与酸的反应性. 这些发现揭示了对解机制和过渡状态的洞察力,这与酶催化有关.
科学领域:
- * 无机化学 无机化学
- *生物有机化学 生物有机化学
- * 机械有机化学 机械有机化学
背景情况:
- *酸盐在生物系统和化学合成中至关重要.
- *双核 (III) 复合体与1,4,7-三环 (tacn) 连接体作为酶活性位点的模型.
- * 了解酸盐的水解是阐明反应机制和设计催化剂的关键.
研究的目的:
- * 调查酸盐的反应性和水解机制协调到二核 (III) 复合体.
- * 为了比较复杂酸盐的水解行为与不复杂的类似物.
- * 阐明基催化水解中涉及的过渡状态结构.
主要方法:
- * 合成和表征五个双核 (III) - 酸盐复合物.
- * 基催化水解的动力学研究.
- * 确定布伦斯特德选择性 (βlg) 值.
- * 测量各种位置的动态同位素效应 (KIE).
主要成果:
- * 酸盐的水解是通过分子内氧化物攻击的特定基催化.
- *复合物 (-1.12) 的布伦斯特德βlg值明显比不复合酸盐 (-0.69) 的负值更高.
- *KIE数据和βlg值表明过渡状态类似于酸盐单水解,而不是二水解.
结论:
- *双核 (III) 复合物为了解酸 Ester 水解提供了有价值的模型.
- *观察到的反应性与蛋白质酸酶-1等酶中的催化机制相似.
- *这些发现有助于设计新型催化剂和理解生物水解过程.
相关概念视频
02:34Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
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...
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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...
02:52Stereoisomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
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Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
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...
02:54Coordination Compounds and Nomenclature
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