A diradical based on odd-electron σ-bonds.

Yang, Wenbang; Zhang, Li; Xiao, Dengmengfei; Feng, Rui; Wang, Wenqing; Pan, Sudip; Zhao, Yue; Zhao, Lili et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

The concept of odd-electron σ-bond was first proposed by Linus Pauling. Species containing such a bond have been recognized as important intermediates encountered in many fields. A number of radicals with a one-electron or three-electron σ-bond have been isolated, however, no example of a diradical based odd-electron σ-bonds has been reported. So far all stable diradicals are based on two s/p-localized or π-delocalized unpaired electrons (radicals). Here, we report a dication diradical that is based on two Se∴Se three-electron σ-bonds. In contrast, the dication of sulfur analogue does not display diradical character but exhibits a closed-shell singlet.