在[CpRu(PhCCAr) ((dppe) ]+中对内部基因与异位维尼利丁异构的DFT研究
Miho Otsuka1, Noriko Tsuchida, Yousuke Ikeda
1Department of Chemistry and Biochemistry, Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan.
Journal of the American Chemical Society
|September 21, 2012
概括
鲁复合物通过直接的1,2转移机制经历内部基因-维尼利丁异构. 较少的电子捐赠的基团有利于迁移,与典型的核友反应相反.
科学领域:
- 有机金属化学 有机金属化学
- 计算化学计算化学
- 反应机制研究 反应机制研究
背景情况:
- 对于理解有机金属反应途径而言,研究复合物的内部基-乙烯异构是至关重要的.
- 连接体的电子和固体效应,如基替代剂和素,显著影响反应机制.
- 准确的计算建模对于阐明过渡金属化学中的复杂反应动态至关重要.
研究的目的:
- 用计算方法研究特定的复合体中的内部基-乙烯-乙烯异构化机制.
- 为了确定替代剂 (R = OMe,Cl,CO2Et) 对异构化途径和激活能量的影响.
- 分析在过渡状态下控制1.2班和迁移偏好的电子因素.
主要方法:
- 采用量子力学和分子力学 (QM/MM) 方法的组合,特别是ONIOM ((B3PW91:UFF).
- 使用密度函数理论 (DFT) 计算与B3PW91函数来分析反应机制.
- 研究了三种不同的模型系统 (I-III),具有不同的QM区域,以捕捉基本的电子效果.
主要成果:
- 对所有研究的复合体来说,异构化通过直接的1,2转移机制进行.
- 途径3,涉及过渡状态中的基因联体方位变化,被确定为最有利的能量.
- 计算的激活能量分别为OME,CO2Et和Cl替代复合物的13.7,15.0和16.4 kcal/mol.
结论:
- 1,2-转移是核友反应的特征,捐赠者-接受者分析提供了关键的见解.
- 电子捐赠替代剂在过渡状态下稳定接受碳的正电荷,而不是迁移的基.
- 与一般的核友反应相反,更少的电子捐赠的基团在这种特定的催化异构化中表现出迁移优势.
相关概念视频
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
Structure of Conjugated Dienes
Introduction
Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
The Claisen rearrangement is a [3,3] sigmatropic rearrangement of allyl vinyl ethers to unsaturated carbonyl compounds. The rearrangement is a concerted pericyclic reaction proceeding via a chair-like transition state.
UV–Vis Spectroscopy: Woodward–Fieser Rules
UV–Visible absorption spectra of conjugated dienes arise from the lowest energy π → π* transitions. The light-absorbing part of the molecule is called the chromophore, and the substituents directly attached to the chromophore are called auxochromes. A strong correlation exists between the absorption maxima, λmax, and the structure of a conjugated π system. The Woodward–Fieser rules predict the value of λmax for a given structure by adding the contributions...
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.


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