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 Barry; R Graeme Soper; Juha Hurmalainen; Akseli Mansikkamäki; Katherine N Robertson; William L McClennan; Alex J Veinot; Tracey L Roemmele; Ulrike Werner-Zwanziger; René T Boeré; Heikki M Tuononen; Jason A C Clyburne; Jason D Masuda

doi:10.1002/anie.201711031

Mono- and Bis(imidazolidinium ethynyl) Cations and Reduction of the Latter To Give an Extended Bis-1,4-([3]Cumulene)-p-carboquinoid System

Angew Chem Int Ed Engl. 2018 Jan 15;57(3):749-754. doi: 10.1002/anie.201711031. Epub 2017 Dec 14.

Affiliations

¹ Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, B3H 3C3, Canada.
² Department of Chemistry, University of Wisconsin-Platteville, Platteville, WI 5, 3818-3099, USA.
³ Department of Chemistry, Nanoscience Centre, University of Jyväskylä, P.O Box 35, University of Jyväskylä, FI-40014, Finland.
⁴ Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada.
⁵ Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, Canada.

PMID: 29152832
DOI: 10.1002/anie.201711031

Abstract

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.

Keywords: N-heterocyclic carbenes; alkynes; cumulenes; propargyl cations; reduction.

Publication types

Research Support, Non-U.S. Gov't