Mono- and Bis(imidazolidinium ethynyl) Cations and Reduction of the Latter To Give an Extended Bis-1,4-([3]Cumulene)-p-carboquinoid System.
Brian M BarryR Graeme SoperJuha HurmalainenAkseli MansikkamäkiKatherine N RobertsonWilliam L McClennanAlex J VeinotTracey L RoemmeleUlrike Werner-ZwanzigerRené T BoeréHeikki M TuononenJason A C ClyburneJason D MasudaPublished in: Angewandte Chemie (International ed. in English) (2017)
An extended π-system containing two [3]cumulene fragments separated by a p-carboquinoid and stabilized by two capping N-heterocyclic carbenes (NHCs) has been prepared. Mono- and bis(imidazolidinium ethynyl) cations have also been synthesized from the reaction of an NHC with phenylethynyl bromide or 1,4-bis(bromoethynyl)benzene. Cyclic voltammetry coupled with synthetic and structural studies showed that the dication is readily reduced to a neutral, singlet bis-1,4-([3]cumulene)-p-carboquinoid as a result of the π-accepting properties of the capping NHCs.
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