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Flexible C-C Bonds: Reversible Expansion, Contraction, Formation, and Scission of Extremely Elongated Single Bonds

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Title: Flexible C-C Bonds: Reversible Expansion, Contraction, Formation, and Scission of Extremely Elongated Single Bonds
Authors: Shimajiri, Takuya Browse this author
Suzuki, Takanori Browse this author
Ishigaki, Yusuke Browse this author →KAKEN DB
Keywords: cyclization
long bonds
redox chemistry
single-crystal-to-single-crystal transformations
thermal cycloreversion
Issue Date: 1-Dec-2020
Publisher: Wiley-Blackwell
Journal Title: Angewandte chemie-international edition
Volume: 59
Issue: 49
Start Page: 22252
End Page: 22257
Publisher DOI: 10.1002/anie.202010615
Abstract: Since carbon-carbon (C-C) covalent bonds are rigid and robust, the bond length is, in general, nearly constant and depends only on the bond order and hybrid orbitals. We report herein direct visualization of the reversible expansion and contraction of a C(sp(3))-C(sp(3)) single bond by light and heat. This flexibility of a C-C bond was demonstrated by X-ray analysis and Raman spectroscopy of hexaphenylethane (HPE)-type hydrocarbons with two spiro-dibenzocycloheptatriene units, the intramolecular [2+2] photocyclization of which and thermal cleavage of the resulting cyclobutane ring both occur in a single-crystalline phase. The force constant of the contracted C-C bond is 1.6 times greater than that of the expanded bond. Since formation of the cyclobutane ring and contraction of the C-C bond lower the HOMO level by approximately 1 eV, the oxidative properties of these HPEs with a flexible C-C bond can be deactivated/activated by light/heat.
Rights: This is the peer reviewed version of the following article: Angewandte Chemie (International ed.) 59(49) December 1, 2020 pp.22252-22257 , which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
Type: article (author version)
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 石垣 侑祐

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