Fluorine deshielding in the proximity of a methyl group. An experimental and theoretical study

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19F chemical shifts are reported for a series of alkyl‐substituted fluoronaphthalenes and related compounds that exhibit steric crowding around the fluorine atom due to the proximity of methyl groups. Comparisons of these chemical shifts with others measured in similar compounds but without the corr...

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Detalles Bibliográficos
Autores principales: Herr, Tomás E., Ferraro, Marta Beatriz, Contreras, Rubén Horacio
Publicado: 1991
Materias:
19F chemical shift theory
19F NMR
1‐Alkyl‐8‐fluoronaphthalenes
Fluorine deshielding
Magnetic shielding tensor calculations
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v29_n5_p422_Gribble
http://hdl.handle.net/20.500.12110/paper_07491581_v29_n5_p422_Gribble
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_07491581_v29_n5_p422_Gribble
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spelling paper:paper_07491581_v29_n5_p422_Gribble2023-06-08T15:45:29Z Fluorine deshielding in the proximity of a methyl group. An experimental and theoretical study Herr, Tomás E. Ferraro, Marta Beatriz Contreras, Rubén Horacio 19F chemical shift theory 19F NMR 1‐Alkyl‐8‐fluoronaphthalenes Fluorine deshielding Magnetic shielding tensor calculations 19F chemical shifts are reported for a series of alkyl‐substituted fluoronaphthalenes and related compounds that exhibit steric crowding around the fluorine atom due to the proximity of methyl groups. Comparisons of these chemical shifts with others measured in similar compounds but without the corresponding methyl groups show that this crowding effect produces a large low‐field shift of the 19F signal. Similar effects, but with an even larger sensitivity to the steric crowding, were recently reported for 17O chemical shifts. The electronic origin for this proximity effect on 19F chemical shifts is analyzed within the molecular orbital theory, at the INDO level, using the inner projections of the polarization propagator technique. It is found that the presence of the methyl group produces an increase in the absolute value of the paramagnetic term of the magnetic shielding constant. Copyright © 1991 John Wiley & Sons Ltd. Fil:Herr, T.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Ferraro, M.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1991 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v29_n5_p422_Gribble http://hdl.handle.net/20.500.12110/paper_07491581_v29_n5_p422_Gribble
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic 19F chemical shift theory
19F NMR
1‐Alkyl‐8‐fluoronaphthalenes
Fluorine deshielding
Magnetic shielding tensor calculations
spellingShingle 19F chemical shift theory
19F NMR
1‐Alkyl‐8‐fluoronaphthalenes
Fluorine deshielding
Magnetic shielding tensor calculations
Herr, Tomás E.
Ferraro, Marta Beatriz
Contreras, Rubén Horacio
Fluorine deshielding in the proximity of a methyl group. An experimental and theoretical study
topic_facet 19F chemical shift theory
19F NMR
1‐Alkyl‐8‐fluoronaphthalenes
Fluorine deshielding
Magnetic shielding tensor calculations
description 19F chemical shifts are reported for a series of alkyl‐substituted fluoronaphthalenes and related compounds that exhibit steric crowding around the fluorine atom due to the proximity of methyl groups. Comparisons of these chemical shifts with others measured in similar compounds but without the corresponding methyl groups show that this crowding effect produces a large low‐field shift of the 19F signal. Similar effects, but with an even larger sensitivity to the steric crowding, were recently reported for 17O chemical shifts. The electronic origin for this proximity effect on 19F chemical shifts is analyzed within the molecular orbital theory, at the INDO level, using the inner projections of the polarization propagator technique. It is found that the presence of the methyl group produces an increase in the absolute value of the paramagnetic term of the magnetic shielding constant. Copyright © 1991 John Wiley & Sons Ltd.
author Herr, Tomás E.
Ferraro, Marta Beatriz
Contreras, Rubén Horacio
author_facet Herr, Tomás E.
Ferraro, Marta Beatriz
Contreras, Rubén Horacio
author_sort Herr, Tomás E.
title Fluorine deshielding in the proximity of a methyl group. An experimental and theoretical study
title_short Fluorine deshielding in the proximity of a methyl group. An experimental and theoretical study
title_full Fluorine deshielding in the proximity of a methyl group. An experimental and theoretical study
title_fullStr Fluorine deshielding in the proximity of a methyl group. An experimental and theoretical study
title_full_unstemmed Fluorine deshielding in the proximity of a methyl group. An experimental and theoretical study
title_sort fluorine deshielding in the proximity of a methyl group. an experimental and theoretical study
publishDate 1991
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07491581_v29_n5_p422_Gribble
http://hdl.handle.net/20.500.12110/paper_07491581_v29_n5_p422_Gribble
work_keys_str_mv AT herrtomase fluorinedeshieldingintheproximityofamethylgroupanexperimentalandtheoreticalstudy
AT ferraromartabeatriz fluorinedeshieldingintheproximityofamethylgroupanexperimentalandtheoreticalstudy
AT contrerasrubenhoracio fluorinedeshieldingintheproximityofamethylgroupanexperimentalandtheoreticalstudy
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