Penotti, Fabio E., Cooper, David L. and Karadakov, Peter B. orcid.org/0000-0002-2673-6804 (2019) Is the S2N2 ring a singlet diradical? Critical analysis of alternative valence bond descriptions. INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY. e25845. ISSN 0020-7608
Abstract
Rival valence bond (VB) descriptions are investigated for the π-electron systems of the sulfur-nitrogen rings S2N2 and S4N4 2+ near equilibrium geometry. The lowest-energy compact spin-coupled generalized VB (SCGVB) descriptions are provided by variational optimization of two configurations that are found to be symmetry related to one another. Optimization instead of symmetry-pure single-configuration SCGVB wave functions introduces three-center SNS or NSN orbitals, which seem to be an unnecessary complication. For neither system is much achieved by mixing competing solutions. Breathing orbital VB (BOVB) calculations for S2N2 confirm NN singlet diradical character to be more important than SS singlet diradical character, but the largest contribution (ca. 60%) comes from the symmetry-determined linear combination of four symmetry-equivalent structures that lack any obvious diradical character. Much the same pattern was consistently found using a simple but robust projection of various SCGVB descriptions for S2N2 onto the basis of BOVB structures (plus an orthogonal complement).
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2018 Wiley Periodicals, Inc. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details. |
Keywords: | breathing orbital valence bond,generalized multiconfiguration spin-coupled,SN and SN,spin-coupled generalized valence bond (SCGVB),π-electron rings |
Dates: |
|
Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) |
Depositing User: | Pure (York) |
Date Deposited: | 21 Jan 2019 11:20 |
Last Modified: | 16 Oct 2024 15:21 |
Published Version: | https://doi.org/10.1002/qua.25845 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1002/qua.25845 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:141386 |
Download
Filename: merged_compressed.pdf
Description: Spin-Coupled Generalized Valence Bond (SCGVB) Descriptions of π-Electron Systems in S2N2 and S4N42+ Rings