从（硅锗杂环丁烯鎓）环丁烯基离子到（硅锗杂环丁烯）环丁烯基自由基再返回。

From a (Silatrigerma)cyclobutenylium Ion to a (Silatrigerma)cyclobutenyl Radical and Back.

作者信息

Lee Vladimir Ya, Ito Yuki, Gapurenko Olga A, Minyaev Ruslan M, Gornitzka Heinz, Sekiguchi Akira

机构信息

Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.

Institute of Physical and Organic Chemistry, Southern Federal University, Rostov on Don 344090, Russian Federation.

出版信息

J Am Chem Soc. 2020 Sep 23;142(38):16455-16460. doi: 10.1021/jacs.0c08052. Epub 2020 Sep 10.

DOI:10.1021/jacs.0c08052

PMID:32862647

Abstract

(Silatrigerma)cyclobutenylium ion salt was readily prepared by the reaction of cyclotrigermene with an equimolar amount of [EtSi(benzene)][B(CF)] in benzene. The homoaromatic nature of was firmly established by its crystallographic analysis, which revealed a highly folded SiGe four-membered ring (40.4°) and a remarkably short transannular Ge-Ge distance of 2.9346(3) Å. The homoaromaticity of was supported by DFT calculations, which confirmed an extensive transannular bonding orbital interaction. One-electron reduction of with potassium graphite resulted in the selective formation of (silatrigerma)cyclobutenyl free radical , which has an allylic-type structure as confirmed by its X-ray and EPR studies. Cation and free radical can be readily interconverted, thus constituting a fully reversible redox pair.

摘要

（硅杂环丁三烯）环丁烯鎓离子盐可通过环三锗烯与等摩尔量的[EtSi(苯)][B(CF)]在苯中反应轻松制备。通过晶体学分析确定了其同芳香性，该分析揭示了一个高度折叠的SiGe四元环（40.4°）以及显著短的跨环Ge-Ge距离2.9346(3) Å。密度泛函理论计算支持了其同芳香性，证实了广泛的跨环键合轨道相互作用。用钾石墨对其进行单电子还原导致选择性形成（硅杂环丁三烯）环丁烯基自由基，通过X射线和电子顺磁共振研究证实其具有烯丙基型结构。阳离子和自由基可以轻松相互转化，从而构成一个完全可逆的氧化还原对。