通过 (M(C5(CH3)5)2)+进行离子稳定:在 (DDQ) 2-中局部化环的理论证据
Science (New York, N.Y.)
|February 20, 1987
概括
研究人员使用铁或复合体稳定了有机离子,从而实现了详细的结构和光谱分析. X射线结晶学揭示了2,3-二-5,6-二enzoquinone dianion 的局部环状结构.
科学领域:
- 有机金属化学 有机金属化学
- 无机化学 无机化学 有机化学
- 有机化学 有机化学
背景情况:
- 稳定有机离子是具有挑战性的,因为它们的高反应性.
- 之前的研究已经探索了稳定活性有机物种的各种方法.
研究的目的:
- 为了合成和表征新的有机.
- 为了研究这些稳定型二离子的结构和电子特性.
主要方法:
- 合成二甲基 (pentamethylcyclopentadienyl) 铁或复合物.
- 使用这些金属复合体稳定有机离子.
- 用于结构确定的X射线晶体学.
- Ab initio分子轨道计算用于电子结构分析.
主要成果:
- 使用[M(Cp*) 2+复合体成功稳定有机二,其中M = Fe或Co和Cp* = pentamethylcyclopentadienyl.
- 确定了该复合体内的2,3-二-5,6-二enzoquinone (DDQ) dianion的晶体结构.
- X射线数据表明DDQ二离子有一个局部的,非芳香的环结构.
- 计算分析支持局部结构,与非局部化的芳香模型形成对比.
结论:
- [M(Cp*) 2+复合体为活性有机二离子提供了有效的稳定.
- 该DDQ dianion采用局部结构,通过实验和计算方法证实了这一点.
- 这项工作为研究其他高度减少的有机物种开辟了道路.
相关概念视频
01:28Stability 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.
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[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.
02:30Stability of Substituted Cyclohexanes
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
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...
01:29Diels–Alder Reaction: Characteristics of Dienes
The Diels–Alder reaction brings together a diene and a dienophile to form a six-membered ring. Both components have unique characteristics that influence the rate of the reaction.
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
01:19Diazonium Group Substitution: –OH and –H
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.