Computation and analysis of 19F substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides

The 19F NMR shieldings for several remotely substituted rigid polycyclic alkyl fluorides with common sets of substituents covering a wide range of electronic effects were calculated using the DFT-GIAO theoretical model. The level of theory, B3LYP/6-311+G(2d,p), was chosen based on trial calculations...

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Autores principales: Adcock, W., Peralta, J.E., Contreras, R.H.
Formato: JOUR
Materias:
19F chemical shift
Bridgehead-substituted bicyclic fluorides
DFT-GIAO
DFT-NBO
Hyperconjugative interactions
NMR
Substituent effects
bridged compound
carbon
fluoride
fluorine
polycyclic hydrocarbon
article
chemical bond
electromagnetic field
electron
geometry
nuclear magnetic resonance spectroscopy
parameter
rigidity
substitution reaction
theoretical model
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_07491581_v41_n7_p503_Adcock
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_07491581_v41_n7_p503_Adcock2023-10-03T15:39:28Z Computation and analysis of 19F substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides Adcock, W. Peralta, J.E. Contreras, R.H. 19F chemical shift Bridgehead-substituted bicyclic fluorides DFT-GIAO DFT-NBO Hyperconjugative interactions NMR Substituent effects bridged compound carbon fluoride fluorine polycyclic hydrocarbon article chemical bond electromagnetic field electron geometry nuclear magnetic resonance spectroscopy parameter rigidity substitution reaction theoretical model The 19F NMR shieldings for several remotely substituted rigid polycyclic alkyl fluorides with common sets of substituents covering a wide range of electronic effects were calculated using the DFT-GIAO theoretical model. The level of theory, B3LYP/6-311+G(2d,p), was chosen based on trial calculations which gave good agreement with experimental values where known. The optimized geometries were used to obtain various molecular parameters (fluorine natural charges, electron occupancies on fluorine of lone pairs and of the C-F bond, and hybridization states) by means of natural bond orbital (NBO) analysis which could help in understanding electronic transmission mechanisms underlying 19F substituent chemical shifts (SCS) in these systems. Linear regression analysis was employed to explore the relationship between the calculated 19F SCS and polar substituent constants and also the NBO derived molecular parameters. The 19F SCS are best described by an electronegativity parameter. The most pertinent molecular parameters appear to be the occupation number of the NBO p-type fluorine lone pair and the occupation number of the C-F antibonding orbital. This trend suggests that in these types of rigid saturated systems hyperconjugative interactions play a key role in determining the 19F SCS. Electrostatic field effects appear to be relatively unimportant. Copyright © 2003 John Wiley & Sons, Ltd. Fil:Peralta, J.E. 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. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_07491581_v41_n7_p503_Adcock
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
Bridgehead-substituted bicyclic fluorides
DFT-GIAO
DFT-NBO
Hyperconjugative interactions
NMR
Substituent effects
bridged compound
carbon
fluoride
fluorine
polycyclic hydrocarbon
article
chemical bond
electromagnetic field
electron
geometry
nuclear magnetic resonance spectroscopy
parameter
rigidity
substitution reaction
theoretical model
spellingShingle 19F chemical shift
Bridgehead-substituted bicyclic fluorides
DFT-GIAO
DFT-NBO
Hyperconjugative interactions
NMR
Substituent effects
bridged compound
carbon
fluoride
fluorine
polycyclic hydrocarbon
article
chemical bond
electromagnetic field
electron
geometry
nuclear magnetic resonance spectroscopy
parameter
rigidity
substitution reaction
theoretical model
Adcock, W.
Peralta, J.E.
Contreras, R.H.
Computation and analysis of 19F substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides
topic_facet 19F chemical shift
Bridgehead-substituted bicyclic fluorides
DFT-GIAO
DFT-NBO
Hyperconjugative interactions
NMR
Substituent effects
bridged compound
carbon
fluoride
fluorine
polycyclic hydrocarbon
article
chemical bond
electromagnetic field
electron
geometry
nuclear magnetic resonance spectroscopy
parameter
rigidity
substitution reaction
theoretical model
description The 19F NMR shieldings for several remotely substituted rigid polycyclic alkyl fluorides with common sets of substituents covering a wide range of electronic effects were calculated using the DFT-GIAO theoretical model. The level of theory, B3LYP/6-311+G(2d,p), was chosen based on trial calculations which gave good agreement with experimental values where known. The optimized geometries were used to obtain various molecular parameters (fluorine natural charges, electron occupancies on fluorine of lone pairs and of the C-F bond, and hybridization states) by means of natural bond orbital (NBO) analysis which could help in understanding electronic transmission mechanisms underlying 19F substituent chemical shifts (SCS) in these systems. Linear regression analysis was employed to explore the relationship between the calculated 19F SCS and polar substituent constants and also the NBO derived molecular parameters. The 19F SCS are best described by an electronegativity parameter. The most pertinent molecular parameters appear to be the occupation number of the NBO p-type fluorine lone pair and the occupation number of the C-F antibonding orbital. This trend suggests that in these types of rigid saturated systems hyperconjugative interactions play a key role in determining the 19F SCS. Electrostatic field effects appear to be relatively unimportant. Copyright © 2003 John Wiley & Sons, Ltd.
format JOUR
author Adcock, W.
Peralta, J.E.
Contreras, R.H.
author_facet Adcock, W.
Peralta, J.E.
Contreras, R.H.
author_sort Adcock, W.
title Computation and analysis of 19F substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides
title_short Computation and analysis of 19F substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides
title_full Computation and analysis of 19F substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides
title_fullStr Computation and analysis of 19F substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides
title_full_unstemmed Computation and analysis of 19F substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides
title_sort computation and analysis of 19f substituent chemical shifts of some bridgehead-substituted polycyclic alkyl fluorides
url http://hdl.handle.net/20.500.12110/paper_07491581_v41_n7_p503_Adcock
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