Structural Assignment of Fluorocyclobutenes by F-19 NMR Spectroscopy - Comparison of Calculated F-19 NMR Shielding Constants with Experimental F-19 NMR Shifts

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22310%2F18%3A43917614" target="_blank" >RIV/60461373:22310/18:43917614 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1002/ejoc.201800482" target="_blank" >http://dx.doi.org/10.1002/ejoc.201800482</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1002/ejoc.201800482" target="_blank" >10.1002/ejoc.201800482</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Structural Assignment of Fluorocyclobutenes by F-19 NMR Spectroscopy - Comparison of Calculated F-19 NMR Shielding Constants with Experimental F-19 NMR Shifts

Popis výsledku v původním jazyce

While optimized reduction of perfluorocyclobutene with LiAlH4 gave quantitative yield of the target 3,3,4,4-tetrafluorocyclobut-1-ene, unoptimized reductions led to complex unseparable mixtures of fluorocyclobutenes. These mixtures showed highly complex 19F NMR spectra, the assignment of which proved to be quite tedious. We hence accomplished a series of single reference computations of 19F NMR magnetic shielding of the corresponding fluorine atoms. Suprisingly, various DFT approaches, including both traditional and advanced functionals, gave highly diverse results with poor correlation of experimental and computed 19F chemical shifts, from which individual fluorocyclobutenes could not be identified. Contrary to that, DLPNO-CCSD method, developed recently as a part of ORCA computational package, gave the shielding values which, although bearing some systematic error, enabled to assign all structures observed. Even slightly better values of the magnetic shielding were obtained by simple HF method using specially tailored IGLO-III basis set. The method developed was successfully employed for assigning the 19F NMR shifts to yet unknown fluorocyclobutenes.

Název v anglickém jazyce

Structural Assignment of Fluorocyclobutenes by F-19 NMR Spectroscopy - Comparison of Calculated F-19 NMR Shielding Constants with Experimental F-19 NMR Shifts

Popis výsledku anglicky

While optimized reduction of perfluorocyclobutene with LiAlH4 gave quantitative yield of the target 3,3,4,4-tetrafluorocyclobut-1-ene, unoptimized reductions led to complex unseparable mixtures of fluorocyclobutenes. These mixtures showed highly complex 19F NMR spectra, the assignment of which proved to be quite tedious. We hence accomplished a series of single reference computations of 19F NMR magnetic shielding of the corresponding fluorine atoms. Suprisingly, various DFT approaches, including both traditional and advanced functionals, gave highly diverse results with poor correlation of experimental and computed 19F chemical shifts, from which individual fluorocyclobutenes could not be identified. Contrary to that, DLPNO-CCSD method, developed recently as a part of ORCA computational package, gave the shielding values which, although bearing some systematic error, enabled to assign all structures observed. Even slightly better values of the magnetic shielding were obtained by simple HF method using specially tailored IGLO-III basis set. The method developed was successfully employed for assigning the 19F NMR shifts to yet unknown fluorocyclobutenes.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10401 - Organic chemistry

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

European Journal of Organic Chemistry

ISSN

1434-193X

e-ISSN

—

Svazek periodika

Neuveden

Číslo periodika v rámci svazku

srpen

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

8

Strana od-do

"3867–3874"

Kód UT WoS článku

000456391900001

EID výsledku v databázi Scopus

2-s2.0-85054880178