Closed-shell and open-shell dual nature of singlet diradical compounds

Kubo, Takashi

Pure and Applied Chemistry, 2023, 1-13

Number of Access:112（2025-05-08 13:46 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/91315

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Title
Closed-shell and open-shell dual nature of singlet diradical compounds
Creator
NRID
1000060324745 1000060324745
ORCID
0000-0001-6809-7396 0000-0001-6809-7396
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Scopus Author ID
55576439300 55576439300
CreatorName
Kubo, Takashi
Subject
closed-shell and open-shell dual nature
coexistence of covalent bonding interaction
cycloaddition reaction
diradicaloid
ICPOC-25
one-dimensional stack
singlet diradical
π-dimer
Description
The final publication is available at https://doi.org/10.1515/pac-2023-0114
Abstract
Unlike triplet diradicals, singlet diradicals can vary in diradical character from 0 % to 100 % depending on linker units that allow two formally unpaired electrons to couple covalently. In principle, the electronic structure of singlet diradicals can be described as a quantum superposition of closed-shell and open-shell structures. This means that, depending on the external environment, singlet diradicals can behave as either closed-shell or open-shell species. This paper summarizes our progress in understanding the electronic structure of π-conjugated singlet diradical molecules in terms of closed-shell and open-shell dual nature. We first discuss the coexistence of intra- and intermolecular covalent bonding interactions in the π-dimer of a singlet diradical molecule. The intra- and intermolecular coupling of two formally unpaired electrons are related to closed-shell and open-shell nature of singlet diradical, respectively. Then we demonstrate the coexistence of the covalent bonding interactions in the one-dimensional stack of singlet diradical molecules having different diradical character. The relative strength of the interactions is varied with the magnitude of singlet diradical index y0. Finally, we show the dual reactivity of a singlet diradical molecule, which undergoes rapid [4 + 2] and [4 + 4] cycloaddition reactions in the dark at room temperature. Closed-shell and open-shell nature endow the singlet diradical molecule with the reaction manner as diene and diradical species, respectively.
Conference Information
Conference Name
International Conference on Physical Organic Chemistry
Conference Sequence
25
Conference Sponsor
International Union of Pure and Applied Chemistry
Conference Date
July 10th to July 15th, 2022
Conference Place
Hiroshima
Conference Country
Japan
Publisher
De Gruyter Open Ltd
Source Title
Pure and Applied Chemistry
Page
1-13
Date of Issued
2023-03-07
Language
English
Handle URL
https://hdl.handle.net/11094/91315
PISSN
00334545
eISSN
13653075
NCID
AA00797859
Relation.isIdenticalTo
DOI (Publisher Version)
https://doi.org/10.1515/pac-2023-0114
Access Rights
open access
oaire:version
Version of Record
Category
会議発表論文 Conference Paper