6,6′-Biindeno[1,2-b]fluorene: an open-shell indenofluorene dimer†

IF 7.6 1区 化学 Q1 CHEMISTRY, MULTIDISCIPLINARY
Himanshu Sharma, Palash Jana, Dibyendu Mallick, Subhajit Bandyopadhyay and Soumyajit Das
{"title":"6,6′-Biindeno[1,2-b]fluorene: an open-shell indenofluorene dimer†","authors":"Himanshu Sharma, Palash Jana, Dibyendu Mallick, Subhajit Bandyopadhyay and Soumyajit Das","doi":"10.1039/D4SC03996C","DOIUrl":null,"url":null,"abstract":"<p >Nakano <em>et al.</em> reported that the antiaromatic indenofluorene (IF) isomers are diradicaloid molecules having varying degrees of open-shell character, with indeno[1,2-<em>b</em>]fluorene displaying a weaker diradical character index (<em>y</em><small><sub>0</sub></small> = 0.072). Unlike 6,12-trimethylsilylethynyl disubstituted [1,2-<em>b</em>]IF, the 6,12-aryl disubstituted [1,2-<em>b</em>]IF derivatives did not show any experimental evidence of diradical properties. This raised the question of whether a [1,2-<em>b</em>]IF dimer would prefer a closed-shell or an open-shell ground state. To address this, herein we report the synthesis of a 6,6′-biindeno[1,2-<em>b</em>]fluorene derivative, which is a [1,2-<em>b</em>]IF dimer, constructed by linking two [1,2-<em>b</em>]IF units with a C–C single bond at carbons 6 and 6′ bearing the largest orbital coefficients for the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO). The C6–C6′ linkage effectively narrowed the HOMO–LUMO gap while the strong desire to avoid <em>s</em>-indacene antiaromaticity restored two Clar sextets in two proaromatic <em>para</em>-quinodimethane subunits, resulting in an open-shell bifluorenylidene-type diradicaloid (<em>y</em><small><sub>0</sub></small> = 0.268) ground state with minor tetraradical character index (<em>y</em><small><sub>1</sub></small> = 0.007). The open-shell nature was confirmed by single crystal X-ray and electron paramagnetic resonance analyses, and supported by theoretical calculations.</p>","PeriodicalId":9909,"journal":{"name":"Chemical Science","volume":" 48","pages":" 20215-20222"},"PeriodicalIF":7.6000,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/sc/d4sc03996c?page=search","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemical Science","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/sc/d4sc03996c","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0

Abstract

Nakano et al. reported that the antiaromatic indenofluorene (IF) isomers are diradicaloid molecules having varying degrees of open-shell character, with indeno[1,2-b]fluorene displaying a weaker diradical character index (y0 = 0.072). Unlike 6,12-trimethylsilylethynyl disubstituted [1,2-b]IF, the 6,12-aryl disubstituted [1,2-b]IF derivatives did not show any experimental evidence of diradical properties. This raised the question of whether a [1,2-b]IF dimer would prefer a closed-shell or an open-shell ground state. To address this, herein we report the synthesis of a 6,6′-biindeno[1,2-b]fluorene derivative, which is a [1,2-b]IF dimer, constructed by linking two [1,2-b]IF units with a C–C single bond at carbons 6 and 6′ bearing the largest orbital coefficients for the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO). The C6–C6′ linkage effectively narrowed the HOMO–LUMO gap while the strong desire to avoid s-indacene antiaromaticity restored two Clar sextets in two proaromatic para-quinodimethane subunits, resulting in an open-shell bifluorenylidene-type diradicaloid (y0 = 0.268) ground state with minor tetraradical character index (y1 = 0.007). The open-shell nature was confirmed by single crystal X-ray and electron paramagnetic resonance analyses, and supported by theoretical calculations.

Abstract Image

6,6'-联茚并[1,2-b]芴:一种开壳茚芴二聚体
Nakano 等人报告说,反芳香族茚并苝(IF)异构体是具有不同程度开壳性质的二元分子,其中茚并苝[1,2-b]芴的二元性质指数较弱(y0 = 0.072)。与 6,12-三甲基硅烷基乙炔基二取代的 [1,2-b]IF 不同,6,12-芳基二取代的 [1,2-b]IF 衍生物没有显示出任何双向性质的实验证据。这就提出了一个问题:[1,2-b]IF 二聚体更倾向于闭壳基态还是开壳基态。为了解决这个问题,我们在本文中报告了一种 6,6'-双茚并[1,2-b]芴衍生物的合成,它是一种[1,2-b]IF 二聚体,由两个[1,2-b]IF 单元通过碳原子 6 和 6'上的 C-C 单键连接而成,碳原子 6 和 6'具有最高占有和最低未占有分子轨道(HOMO 和 LUMO)的最大轨道系数。C6-C6' 连接有效地缩小了 HOMO-LUMO 间隙,同时,由于强烈希望避免 s-indacene 反芳香性,因此在两个原芳香族对二醌甲烷亚基中恢复了两个 Clar 六元组,从而形成了开壳双芴型二拉德基态(y0 = 0.268),并具有较小的四拉德特性指数(y1 = 0.007)。开壳性质通过单晶 X 射线和电子顺磁共振分析得到证实,并得到理论计算的支持。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
Chemical Science
Chemical Science CHEMISTRY, MULTIDISCIPLINARY-
CiteScore
14.40
自引率
4.80%
发文量
1352
审稿时长
2.1 months
期刊介绍: Chemical Science is a journal that encompasses various disciplines within the chemical sciences. Its scope includes publishing ground-breaking research with significant implications for its respective field, as well as appealing to a wider audience in related areas. To be considered for publication, articles must showcase innovative and original advances in their field of study and be presented in a manner that is understandable to scientists from diverse backgrounds. However, the journal generally does not publish highly specialized research.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信