Synthesis and properties of compounds with a bond length beyond 2Å

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K21194
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 33:Organic chemistry and related fields
• Research Institution: Osaka University
• Principal Investigator: Kubo Takashi 大阪大学, 大学院理学研究科, 教授 (60324745)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: 炭素－炭素単結合 / 超結合 / ２Å / 共有結合 / ビラジカル

Outline of Final Research Achievements

This study aims to explore new possibilities in organic compounds by focusing on the length of single bonds as non-standard states of carbon-carbon bonding, creating compounds with single bonds exceeding 2 Angstrom, elucidating the electronic structure of their unique bonding state, and exploring their distinctive reactivity and physical properties. In fact, successful isolation of compounds with single bonds of 2.04 Angstrom; in length, in five steps starting from commercially available fulorenone, was achieved. Various spectroscopic measurements and quantum chemical calculations revealed that the long single bond has sufficient covalent bonding character. Additionally, in order to investigate interactions between long bonds, attempts were made to synthesize two compounds having long bonds within a molecule, and successful generation of the precursor dianion species was achieved.

Free Research Field

構造有機化学

Academic Significance and Societal Importance of the Research Achievements

共有結合は有機化学にとって最も根本的な概念であり、炭素‐炭素単結合は共有結合を理解するにあたって最もシンプルなモデルとなる。その炭素‐炭素単結合の限界点を探ることで共有結合とは何か、何をもってどう判断するか、という学術的問いに答えることができる。その限界点にほぼ達した化合物の単離に成功した本研究は、共有結合性の有無をいかにして調べ、得られた測定結果をどのように解釈するべきかを提示できた点で、学術的に非常に意義深いものであると言える。