関連する実験動画

Updated: Aug 28, 2025

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

レーニウム水素の相関する熱力学および運動的水分性

Matthew R Espinosa¹, Mehmed Z Ertem², Mariam Barakat³

¹Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States.

Journal of the American Chemical Society

|September 21, 2022

まとめ

この研究では,レニウム複合体から様々な受容体へのヒドリド移転反応を調査した. 熱力学的な駆動力は一般的に反応速度を増加させますが,ステリック要因は,触媒設計に不可欠な水素移転運動性に大きく影響します.

科学分野:

有機金属化学
反応運動学
コンピュータ化学

背景:

ハイドリドの移転を理解することは,触媒の鍵です.
レニウムビピリジン複合体は,関連するヒドリドドナーである.
反応速度を予測するには,熱力学および運動的要因を理解する必要があります.

研究の目的:

Re(R-bpy) ((CO) 3H複合体からのヒドリド移転の運動を決定する.
これらのレニウム複合体の熱力学的水分性を確立する.
動力学的および熱力学的パラメータを相関させ,水素移転率に影響を与える要因を探求する.

主な方法:

二酸化炭素とNヘテロサイクルへのヒドリド移転の運動研究.
熱力学的な水分性を決定する計算方法 (DFT).
線形自由エネルギー関係 (LFER),運動同位体効果,ハメット解析,ブロンステッドα値を用いた分析.

主要な成果:

熱力学的な駆動力によってヒドリドの移転速度は一般的に増加する.
運動同位体の効果は,駆動力によって逆から正常に変化します.
ハメット分析では電子効果に対する感受性が低下し駆動力が増加します
ブロンステッドのα値とDFTは,マーカス理論に適用可能な反応を示唆する.
熱力学的予測の限界を強調して,ステリック効果は予測速度を大幅に逸脱する.

結論:

熱力学的な推進力は,ヒドリド移転速度の重要な予測因子ですが,唯一の予測因子ではありません.
ステリック因子は反応運動を調節する上で重要な役割を果たす.
触媒の設計は,熱力学とステリックの両方の影響を考慮して最適の性能を得なければならない.

さらに関連する動画

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Published on: April 8, 2020

A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements

A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements

Published on: July 19, 2016

関連する概念動画

Thermochemical Equations

Thermochemical Equations

For a chemical reaction (the system) carried out at constant pressure – with the only work done caused by expansion or contraction – the enthalpy of reaction (also called the heat of reaction, ΔHrxn) is equal to the heat exchanged with the surroundings (qp).

Acid-Catalyzed Hydration of Alkenes

Acid-Catalyzed Hydration of Alkenes

Alkenes react with water in the presence of an acid to form an alcohol. In the absence of acid, hydration of alkenes does not occur at a significant rate, and the acid is not consumed in the reaction. Therefore, alkene hydration is an acid-catalyzed reaction.

Hess's Law

Hess's Law

There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally, or calculate it from other experimentally determined enthalpy changes. Some reactions are difficult, if not impossible, to investigate and make accurate measurements for experimentally. And even when a reaction is not hard to perform or measure, it is convenient to be able to determine the heat involved in a reaction without having to perform an experiment.

Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control

Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control

The addition of a hydrogen halide to 1,3-butadiene gives a mixture of 1,2- and 1,4-adducts. Since more substituted alkenes are more stable, the 1,4-adduct is expected to be the major product. However, the product distribution is strongly influenced by temperature; low temperature favors the 1,2-adduct, whereas the 1,4-adduct is predominant at high temperature.

Radical Halogenation: Thermodynamics

Radical Halogenation: Thermodynamics

The thermodynamic favorability of a reaction is determined by the change in Gibbs free energy (ΔG). ΔG has two components- enthalpy (ΔH) and entropy (ΔS). The entropy component is negligible for alkane halogenation because the number of reactants and product molecules are equal. In this case, the ΔG is governed only by the enthalpy component. The most crucial factor that determines ΔH is the strength of the bonds. ΔH can be determined by comparing the energy...

Enthalpy and Heat of Reaction

Enthalpy and Heat of Reaction

Combustion, commonly known as burning, is a reaction in which a substance reacts with an oxidizing agent, which in most cases is molecular oxygen, to liberate energy in the form of heat, light, or sound. The heat of combustion is also known as the enthalpy of combustion. The energy released when one mole of a substance undergoes complete combustion at constant pressure is called molar heat of combustion. Combustion reactions are exothermic; that is, they release energy, and their ΔH sign...