Structural Assignment of Fluorocyclobutenes by 19 F NMR Spectroscopy – Comparison of Calculated 19 F NMR Shielding Constants with Experimental 19 F NMR Shifts
Although the optimized reduction of perfluorocyclobutene with LiAlH 4 gave a quantitative yield of the target 3,3,4,4‐tetrafluorocyclobut‐1‐ene, unoptimized reductions led to complex inseparable mixtures of fluorocyclobutenes. These mixtures showed highly complex 19 F NMR spectra, the assignment of...
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crwiley:10.1002/ejoc.201800482 2024-06-02T08:12:48+00:00 Structural Assignment of Fluorocyclobutenes by 19 F NMR Spectroscopy – Comparison of Calculated 19 F NMR Shielding Constants with Experimental 19 F NMR Shifts Kučnirová, Kateřina Šimůnek, Ondřej Rybáčková, Markéta Kvíčala, Jaroslav Ministry of Education, Youth and Sports Ministry of Education, Youth and Sports Ministry of Education, Youth and Sports 2018 http://dx.doi.org/10.1002/ejoc.201800482 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fejoc.201800482 https://onlinelibrary.wiley.com/doi/full/10.1002/ejoc.201800482 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor European Journal of Organic Chemistry volume 2018, issue 27-28, page 3867-3874 ISSN 1434-193X 1099-0690 journal-article 2018 crwiley https://doi.org/10.1002/ejoc.201800482 2024-05-03T10:59:48Z Although the optimized reduction of perfluorocyclobutene with LiAlH 4 gave a quantitative yield of the target 3,3,4,4‐tetrafluorocyclobut‐1‐ene, unoptimized reductions led to complex inseparable mixtures of fluorocyclobutenes. These mixtures showed highly complex 19 F NMR spectra, the assignment of which was quite tedious. Hence, we accomplished a series of single‐reference computations of the 19 F NMR magnetic shieldings of the corresponding fluorine atoms. Surprisingly, various DFT approaches, including both traditional and advanced functionals, gave highly diverse results with poor correlations between the experimental and computed 19 F chemical shifts, and the individual fluorocyclobutenes could not be identified. In contrast, the domain‐based local pair natural orbital coupled clusters (DLPNO‐CCSD) method, developed recently as a part of the ORCA computational package, gave shielding values that enabled the assignment of all structures observed, albeit with some systematic errors. Slightly better magnetic shielding values were obtained by a simple Hartree–Fock (HF) method with a specially tailored IGLO‐III basis set. The method developed was successfully employed for the assignment of the 19 F NMR shifts of unknown fluorocyclobutenes. Article in Journal/Newspaper Orca Wiley Online Library Hartree ENVELOPE(-44.716,-44.716,-60.783,-60.783) European Journal of Organic Chemistry 2018 27-28 3867 3874 |
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Wiley Online Library |
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crwiley |
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English |
description |
Although the optimized reduction of perfluorocyclobutene with LiAlH 4 gave a quantitative yield of the target 3,3,4,4‐tetrafluorocyclobut‐1‐ene, unoptimized reductions led to complex inseparable mixtures of fluorocyclobutenes. These mixtures showed highly complex 19 F NMR spectra, the assignment of which was quite tedious. Hence, we accomplished a series of single‐reference computations of the 19 F NMR magnetic shieldings of the corresponding fluorine atoms. Surprisingly, various DFT approaches, including both traditional and advanced functionals, gave highly diverse results with poor correlations between the experimental and computed 19 F chemical shifts, and the individual fluorocyclobutenes could not be identified. In contrast, the domain‐based local pair natural orbital coupled clusters (DLPNO‐CCSD) method, developed recently as a part of the ORCA computational package, gave shielding values that enabled the assignment of all structures observed, albeit with some systematic errors. Slightly better magnetic shielding values were obtained by a simple Hartree–Fock (HF) method with a specially tailored IGLO‐III basis set. The method developed was successfully employed for the assignment of the 19 F NMR shifts of unknown fluorocyclobutenes. |
author2 |
Ministry of Education, Youth and Sports Ministry of Education, Youth and Sports Ministry of Education, Youth and Sports |
format |
Article in Journal/Newspaper |
author |
Kučnirová, Kateřina Šimůnek, Ondřej Rybáčková, Markéta Kvíčala, Jaroslav |
spellingShingle |
Kučnirová, Kateřina Šimůnek, Ondřej Rybáčková, Markéta Kvíčala, Jaroslav Structural Assignment of Fluorocyclobutenes by 19 F NMR Spectroscopy – Comparison of Calculated 19 F NMR Shielding Constants with Experimental 19 F NMR Shifts |
author_facet |
Kučnirová, Kateřina Šimůnek, Ondřej Rybáčková, Markéta Kvíčala, Jaroslav |
author_sort |
Kučnirová, Kateřina |
title |
Structural Assignment of Fluorocyclobutenes by 19 F NMR Spectroscopy – Comparison of Calculated 19 F NMR Shielding Constants with Experimental 19 F NMR Shifts |
title_short |
Structural Assignment of Fluorocyclobutenes by 19 F NMR Spectroscopy – Comparison of Calculated 19 F NMR Shielding Constants with Experimental 19 F NMR Shifts |
title_full |
Structural Assignment of Fluorocyclobutenes by 19 F NMR Spectroscopy – Comparison of Calculated 19 F NMR Shielding Constants with Experimental 19 F NMR Shifts |
title_fullStr |
Structural Assignment of Fluorocyclobutenes by 19 F NMR Spectroscopy – Comparison of Calculated 19 F NMR Shielding Constants with Experimental 19 F NMR Shifts |
title_full_unstemmed |
Structural Assignment of Fluorocyclobutenes by 19 F NMR Spectroscopy – Comparison of Calculated 19 F NMR Shielding Constants with Experimental 19 F NMR Shifts |
title_sort |
structural assignment of fluorocyclobutenes by 19 f nmr spectroscopy – comparison of calculated 19 f nmr shielding constants with experimental 19 f nmr shifts |
publisher |
Wiley |
publishDate |
2018 |
url |
http://dx.doi.org/10.1002/ejoc.201800482 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fejoc.201800482 https://onlinelibrary.wiley.com/doi/full/10.1002/ejoc.201800482 |
long_lat |
ENVELOPE(-44.716,-44.716,-60.783,-60.783) |
geographic |
Hartree |
geographic_facet |
Hartree |
genre |
Orca |
genre_facet |
Orca |
op_source |
European Journal of Organic Chemistry volume 2018, issue 27-28, page 3867-3874 ISSN 1434-193X 1099-0690 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/ejoc.201800482 |
container_title |
European Journal of Organic Chemistry |
container_volume |
2018 |
container_issue |
27-28 |
container_start_page |
3867 |
op_container_end_page |
3874 |
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1800759359391662080 |