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Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion

Owing to the increased proton affinity that results from additional negative charges, multiply-charged anions have been proposed as one route to prepare and access a range of new and powerful “superbases”. Paradoxically, while the additional electrons in polyanions increase basicity they serve to di...

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Autores principales: Poad, Berwyck L. J., Reed, Nicholas D., Hansen, Christopher S., Trevitt, Adam J., Blanksby, Stephen J., Mackay, Emily G., Sherburn, Michael S., Chan, Bun, Radom, Leo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6024202/
https://www.ncbi.nlm.nih.gov/pubmed/30034765
http://dx.doi.org/10.1039/c6sc01726f
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author Poad, Berwyck L. J.
Reed, Nicholas D.
Hansen, Christopher S.
Trevitt, Adam J.
Blanksby, Stephen J.
Mackay, Emily G.
Sherburn, Michael S.
Chan, Bun
Radom, Leo
author_facet Poad, Berwyck L. J.
Reed, Nicholas D.
Hansen, Christopher S.
Trevitt, Adam J.
Blanksby, Stephen J.
Mackay, Emily G.
Sherburn, Michael S.
Chan, Bun
Radom, Leo
author_sort Poad, Berwyck L. J.
collection PubMed
description Owing to the increased proton affinity that results from additional negative charges, multiply-charged anions have been proposed as one route to prepare and access a range of new and powerful “superbases”. Paradoxically, while the additional electrons in polyanions increase basicity they serve to diminish the electron binding energy and thus, it had been thought, hinder experimental synthesis. We report the synthesis and isolation of the ortho-diethynylbenzene dianion (ortho-DEB(2–)) and present observations of this novel species undergoing gas-phase proton-abstraction reactions. Using a theoretical model based on Marcus–Hush theory, we attribute the stability of ortho-DEB(2–) to the presence of a barrier that prevents spontaneous electron detachment. The proton affinity of 1843 kJ mol(–1) calculated for this dianion superbase using high-level quantum chemistry calculations significantly exceeds that of the lithium monoxide anion, the most basic system previously prepared. The ortho-diethynylbenzene dianion is therefore the strongest base that has been experimentally observed to date.
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spelling pubmed-60242022018-07-20 Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion Poad, Berwyck L. J. Reed, Nicholas D. Hansen, Christopher S. Trevitt, Adam J. Blanksby, Stephen J. Mackay, Emily G. Sherburn, Michael S. Chan, Bun Radom, Leo Chem Sci Chemistry Owing to the increased proton affinity that results from additional negative charges, multiply-charged anions have been proposed as one route to prepare and access a range of new and powerful “superbases”. Paradoxically, while the additional electrons in polyanions increase basicity they serve to diminish the electron binding energy and thus, it had been thought, hinder experimental synthesis. We report the synthesis and isolation of the ortho-diethynylbenzene dianion (ortho-DEB(2–)) and present observations of this novel species undergoing gas-phase proton-abstraction reactions. Using a theoretical model based on Marcus–Hush theory, we attribute the stability of ortho-DEB(2–) to the presence of a barrier that prevents spontaneous electron detachment. The proton affinity of 1843 kJ mol(–1) calculated for this dianion superbase using high-level quantum chemistry calculations significantly exceeds that of the lithium monoxide anion, the most basic system previously prepared. The ortho-diethynylbenzene dianion is therefore the strongest base that has been experimentally observed to date. Royal Society of Chemistry 2016-09-01 2016-06-20 /pmc/articles/PMC6024202/ /pubmed/30034765 http://dx.doi.org/10.1039/c6sc01726f Text en This journal is © The Royal Society of Chemistry 2016 https://creativecommons.org/licenses/by/3.0/This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0)
spellingShingle Chemistry
Poad, Berwyck L. J.
Reed, Nicholas D.
Hansen, Christopher S.
Trevitt, Adam J.
Blanksby, Stephen J.
Mackay, Emily G.
Sherburn, Michael S.
Chan, Bun
Radom, Leo
Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion
title Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion
title_full Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion
title_fullStr Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion
title_full_unstemmed Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion
title_short Preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion
title_sort preparation of an ion with the highest calculated proton affinity: ortho-diethynylbenzene dianion
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6024202/
https://www.ncbi.nlm.nih.gov/pubmed/30034765
http://dx.doi.org/10.1039/c6sc01726f
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