Direct Observation of a Fundamental Arylium Species Using Photoelectron Spectroscopy: Singlet-Triplet Gap in Phenylium.

IF 15.6 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Journal of the American Chemical Society Pub Date : 2025-05-11 DOI:10.1021/jacs.5c01851

Megan R Bentley,Ugo Jacovella,Jean-Christophe Loison,Myriam Drissi,Gustavo A Garcia,Séverine Boyé-Péronne,Peter R Franke,John F Stanton,Bérenger Gans

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Abstract

Reactive intermediates such as aryl cations play crucial roles in organic and astrochemical processes, yet their characterization remains a significant experimental challenge. The present study offers the first partially vibrationally resolved photoelectron spectrum of the phenyl radical (C6H5), focusing on ionization thresholds to the lowest singlet and triplet states of its cation. Using synchrotron-based photoelectron spectroscopy, we directly determine the adiabatic ionization energy of the first triplet state of phenylium (C6H5+, IEad(ã+ ← X̃) = 9.300(10) eV), and use this as an anchor to derive the singlet-triplet energy gap (ΔE(S-T) = 1.043(32) eV) with assistance from advanced quantum chemical computations. These findings provide new constraints to thermochemical properties essential in arylium ground state determination (and thus essential for a better understanding of arylium chemistry), and establish a framework for future joint spectroscopic-computational studies of more complex arylium compounds.

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用光电子能谱直接观察一种基本的芳族：苯基中的单重态-三重态间隙。

芳基阳离子等反应中间体在有机和天体化学过程中起着至关重要的作用，但它们的表征仍然是一个重大的实验挑战。本研究提供了苯基自由基（C6H5）的第一个部分振动分辨光电子谱，重点关注其阳离子的最低单线态和三重态的电离阈值。利用同步光电子能谱，我们直接确定了苯的第一三重态绝热电离能（C6H5+, ead （ã+←X→）= 9.300(10)eV），并以此为锚点，借助先进的量子化学计算推导出单重态-三重态能隙(ΔE（S-T) = 1.043(32) eV）。这些发现为确定aryum基态所必需的热化学性质提供了新的限制（因此对更好地理解aryum化学至关重要），并为未来更复杂的aryum化合物的联合光谱-计算研究建立了框架。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of the American Chemical Society 化学-化学综合

CiteScore

24.40

自引率

6.00%

发文量

2398

审稿时长

1.6 months

期刊介绍： The flagship journal of the American Chemical Society, known as the Journal of the American Chemical Society (JACS), has been a prestigious publication since its establishment in 1879. It holds a preeminent position in the field of chemistry and related interdisciplinary sciences. JACS is committed to disseminating cutting-edge research papers, covering a wide range of topics, and encompasses approximately 19,000 pages of Articles, Communications, and Perspectives annually. With a weekly publication frequency, JACS plays a vital role in advancing the field of chemistry by providing essential research.