N-Carbazolyl π-Radical and Its Antiaromatic Nitrenium Ion:阈值光电子能谱研究。

IF 2.7 2区 化学 Q3 CHEMISTRY, PHYSICAL
Mayank Saraswat, Adrian Portela-Gonzalez, Enrique Mendez-Vega, Wolfram Sander, Patrick Hemberger
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引用次数: 0

摘要

了解杂环基及其阳离子的结构和性质对于阐明反应机理至关重要,因为它们是用途广泛的合成中间体。在这项工作中,通过热解生成了 N-咔唑基 1,并利用光离子质量选择阈值光电子能谱结合可调谐真空紫外同步辐射对其进行了表征。N-Centered 自由基 1 被归类为 π 自由基 (2B1),其非配对电子在咔唑的中心五元环上脱位。从自由基 1 到其单态 1+(1A1) 和三态 1+(3B2) 阳离子的绝热电离能分别为 7.70 ± 0.03 和 8.14 ± 0.03 eV。反芳香族腈离子 1+ 呈单线基态,实验单线-三线能隙 (ΔES-T) 为 -0.44 eV (10.1 kcal/mol),与理论非常吻合。由于单占分子轨道的稳定,以 N 为中心的自由基比以 C 为中心的自由基具有更高的电离能。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
N-Carbazolyl π-Radical and Its Antiaromatic Nitrenium Ion: A Threshold Photoelectron Spectroscopic Study.

Understanding the structure and properties of heterocyclic radicals and their cations is crucial for elucidating reaction mechanisms as they serve as versatile synthetic intermediates. In this work, the N-carbazolyl radical 1 was generated via pyrolysis and characterized using photoion mass-selected threshold photoelectron spectroscopy coupled with tunable vacuum-ultraviolet synchrotron radiation. The N-centered radical 1 is classified as a π-radical (2B1), with the unpaired electron found to be delocalized over the central five-membered ring of the carbazole. Adiabatic ionization energies corresponding to the transition from radical 1 to its singlet 1+(1A1) and triplet 1+(3B2) cations were determined to be 7.70 ± 0.03 and 8.14 ± 0.03 eV, respectively. The antiaromatic nitrenium ion 1+ exhibits a singlet ground state with an experimental singlet-triplet energy gap (ΔES-T) of -0.44 eV (10.1 kcal/mol), in very good agreement with theory. N-centered radicals are found to have a higher ionization energy than their C-centered analogues due to stabilization of the singly occupied molecular orbital.

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来源期刊
The Journal of Physical Chemistry A
The Journal of Physical Chemistry A 化学-物理:原子、分子和化学物理
CiteScore
5.20
自引率
10.30%
发文量
922
审稿时长
1.3 months
期刊介绍: The Journal of Physical Chemistry A is devoted to reporting new and original experimental and theoretical basic research of interest to physical chemists, biophysical chemists, and chemical physicists.
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