来自XMS-CASPT2基准的单个氧反应的自旋受限描述
Max Winslow1, Alexander Hazelby1, David Robinson1
1Department of Chemistry and Forensics, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom.
The journal of physical chemistry. A
|May 13, 2024
概括
旋转受限密度函数理论 (DFT) 准确地预测单片氧反应,克服了复杂分子不受限制的DFT的局限性. 这种计算方法现在可靠地研究有机化学中的单点氧反应性.
科学领域:
- 计算化学的计算化学
- 量子化学 是一个量子化学.
- 有机反应机制 有机反应机制
背景情况:
- 单片氧反应在化学和生物学中至关重要,但在复杂系统中预测它们的结果具有挑战性.
- 传统的密度函数理论 (DFT) 方法与单片氧的退化电子状态作斗争,导致旋转污染.
- 准确的理论预测单片氧反应性对于理解和控制这些反应至关重要.
研究的目的:
- 为了证明自旋受限DFT在准确描述单片氧反应路径方面的有效性.
- 通过高层次量子化学方法 (XMS-CASPT2) 验证自旋受限制的DFT预测.
- 建立自旋受限制的DFT作为研究有机分子中单片氧反应的可靠工具.
主要方法:
- 利用自旋受限密度函数理论 (DFT) 来建模四种原型单片氧反应.
- 采用多参考方法,特别是XMS-CASPT2,用于基准测试和验证.
- 分析了电子结构的变化,包括在1Δg状态中破坏轨道退化.
主要成果:
- 旋转受限制的DFT成功预测了单片氧的反应路径,避免了旋转污染问题.
- 基准测试证实,DFT准确地捕捉了与有机基质相互作用时单片氧的π*轨道中退化的升起.
- DFT的计算效率允许研究中等到大型有机分子.
结论:
- 旋转受限制的DFT是一种适合和准确的计算方法,用于研究单片氧反应.
- 这种方法克服了理论研究中与旋转污染相关的先前限制.
- 这些发现使得DFT可靠地用于预测涉及单一氧的复杂有机系统中的反应性.
相关概念视频
01:17Spin–Spin Coupling: One-Bond Coupling
957
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
957
01:08Spin–Spin Coupling Constant: Overview
911
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
911
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
1.0K
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
1.0K
01:17Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
2.5K
Ideally, an unpaired electron shows a single peak in the EPR spectrum due to the transition between the two spin energy states. However, coupling interactions can occur between the spins of the unpaired electron and any neighboring spin-active nuclei. This hyperfine coupling results in hyperfine splitting, where the EPR signal is split into multiplets. The signals split into 2nI + 1 peaks, where n is the number of equivalent nuclei and I is the nuclear spin. These splitting patterns provide...
2.5K
01:08NMR Spectroscopy: Spin–Spin Coupling
1.3K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
1.3K
02:42Valence Bond Theory
8.5K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
8.5K