相关实验视频

Updated: Apr 23, 2026

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex

Published on: July 27, 2022

化的阴离子调制反应性-皇冠复合物

Matthew R Kita¹, Alexander J M Miller

¹Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.

Journal of the American Chemical Society

|October 3, 2014

概括

这项研究引入了一种新的-皇冠以太联结体,可以以多种方式协调. 这种连接体促进了阴离子促进的激活,离子显著加快了反应速度.

科学领域:

协调化学协调化学
有机金属化学有机金属化学
超分子化学超分子化学

背景情况:

开发多联体对催化至关重要.
子连接体提供稳定性和定义的协调几何形状.
阿萨-皇冠乙烯以其阴离子结合特性而闻名.

研究的目的:

合成和表征一种新型的多牙联体,结合了和阿扎皇冠以太基.
为了研究连接体与各种金属中心的协调行为.
探索产生的复合体在促催化反应,特别是激活中的实用性.

主要方法:

冠以太结合物的合成.
使用光谱技术 (NMR,IR,质谱) 进行连接体和金属复合物的表征.
结晶学分析以确定协调模式.
动力学研究,以评估催化活性和提高激活和H/D交换反应的速度.

主要成果:

这种新型连接体表现出灵活的协调,采用三牙,四牙和五牙模式.
协调模式可以通过易斯基位移和阴离子-宏循环相互作用 (Li+,Na+) 调整.
一个化单酸盐复合体,五连接,证明了有效的酸盐促进激活.
与相比,酸加速了H/D的汇率高达250倍,而汇率取决于酸的度.

结论:

设计的钉冠以太联体提供了多样化的协调能力.
阴离子-宏环相互作用显著影响连接体结合和催化活性.
该系统提供了一个可调节的平台,用于子促进的激活,在催化中具有潜在的应用.

更多相关视频

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

Published on: March 20, 2017

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Published on: March 20, 2014

相关概念视频

Radical Reactivity: Intramolecular vs Intermolecular

Radical Reactivity: Intramolecular vs Intermolecular

Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak...

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.

Regioselectivity and Stereochemistry of Hydroboration

Regioselectivity and Stereochemistry of Hydroboration

A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...

Photochemical Electrocyclic Reactions: Stereochemistry

Photochemical Electrocyclic Reactions: Stereochemistry

The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation

Thermal Electrocyclic Reactions: Stereochemistry

Thermal Electrocyclic Reactions: Stereochemistry

The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement

[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement

The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.