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Updated: Mar 8, 2026

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
Direct Detection of a Chemical Equilibrium between a Localized Singlet Diradical and Its σ-Bonded Species by
Shohei Yoshidomi1, Megumi Mishima1, Shin Seyama1,2
1Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.
Abstract:
Localized singlet diradicals are key intermediates in bond homolyses. The singlet diradicals are energetically much less stable than the σ-bonded species. In general, only one-way reactions from diradicals to σ-bonded species are observed. In this study, a thermal equilibrium between a singlet 1,2-diazacyclopentane-3,5-diyl diradical and the corresponding σ-bonded species was directly observed. The singlet diradical was more stable than the σ-bonded species. The solvent effect clarified key features, such as the zwitterionic character of the singlet diradical. The effect of the nitrogen atoms is discussed in detail.
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