相关实验视频
Updated: May 24, 2026

10:44
Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
一个可分离的NHC稳定型烯基离子:合成和结构特征
Hiroaki Tanaka1, Masaaki Ichinohe, Akira Sekiguchi
1Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Journal of the American Chemical Society
|March 17, 2012
概括
研究人员合成了一种新型的烯-N-异环碳素 (NHC) 复合物及其相应的基离子. 这项研究促进了对基于的化合物及其独特电子性质的理解.
科学领域:
- 有机金属化学 有机金属化学
- 化学 化学 化学
- 碳烯化学 碳烯化学
背景情况:
- N-异环碳 (NHCs) 是有机金属化学中的多功能联体.
- 碳的类相似物西利是具有独特电子性质的反应性物种.
- 通过NHC配体稳定烯是一种活跃的研究领域.
研究的目的:
- 为了合成和表征一种新型的基替代基烯-NHC复合物.
- 为了研究烯-NHC复合物的单电子氧化.
- 确定所得到的NHC稳定型烯基基离子的结构和电子特性.
主要方法:
- 在存在NHC的情况下,使用KC(8) 减少dibromosilane的降解解.
- 一个电子的氧化使用一个tris(4-tert-butyldimethylsilyl-2,3,5,6-tetrafluorophenyl) 酸盐.
- 射线晶体学和电子磁共振 (EPR) 光谱学用于结构和电子特征.
主要成果:
- 对空气和水分敏感的烯-NHC复合物 bis ((tri-tert-butylsilyl) 烯- ((1,3,4,5-tetramethylimidazol-2-ylidene) 的合成和分离.
- 成功的单电子氧化形成NHC稳定型西基离子.
- 结构特征揭示了一个平面结构的根基与一个π-根基的性质.
结论:
- 这项研究证明了烯-NHC复合物的成功合成和稳定.
- 该NHC连接体有效地稳定了烯部分,即使在一电子氧化.
- 基离子的平面,π-根性质为基于的根性物种的电子结构提供了洞察力.
相关概念视频
Radical Reactivity: Steric Effects
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic factors, steric factors also account...
Along with electronic factors, steric factors also account...
Aromatic Hydrocarbon Cations: Structural Overview
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group with both...
Removing one hydrogen from the intervening CH2 group with both...
Radicals: Electronic Structure and Geometry
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Carbocations
Carbocations are one of the reaction intermediates formed during several nucleophilic substitutions or elimination reactions. A carbocation is an electron-deficient species with the central carbon atom having six electrons and three bonded atoms. The central carbon in a carbocation is sp2 hybridized with trigonal planar geometry. It has an empty p orbital perpendicular to the plane of the structure that can accept electrons. Thus, carbocations act as strong electrophiles and may react with any...
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.

![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)