Qualitative study of substituent effects on NMR15N and 17O chemical shifts

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A qualitative approach to analyze the electronic origin of substituent effects on the paramagnetic part of chemical shifts is described and applied to few model systems, where its potentiality can be appreciated. The formulation of this approach is based on the following grounds. The influence of di...

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Autores principales: Contreras, Rubén Horacio, Pagola, Gabriel Ignacio, Melo, Juan Ignacio
Publicado: 2009
Materias:
Charge transfer interaction
Conjugative effect
Electronic origin
Hyperconjugative interactions
Intramolecular interactions
Magnetic shielding constant
Model system
Qualitative approach
Qualitative study
Second orders
Substituent effect
Virtual excitations
Charge transfer
Ion exchange
Sulfur compounds
Chemical shift
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895639_v113_n36_p9874_Contreras
http://hdl.handle.net/20.500.12110/paper_10895639_v113_n36_p9874_Contreras
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_10895639_v113_n36_p9874_Contreras
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spelling paper:paper_10895639_v113_n36_p9874_Contreras2023-06-08T16:06:26Z Qualitative study of substituent effects on NMR15N and 17O chemical shifts Contreras, Rubén Horacio Pagola, Gabriel Ignacio Melo, Juan Ignacio Charge transfer interaction Conjugative effect Electronic origin Hyperconjugative interactions Intramolecular interactions Magnetic shielding constant Model system Qualitative approach Qualitative study Second orders Substituent effect Virtual excitations Charge transfer Ion exchange Sulfur compounds Chemical shift A qualitative approach to analyze the electronic origin of substituent effects on the paramagnetic part of chemical shifts is described and applied to few model systems, where its potentiality can be appreciated. The formulation of this approach is based on the following grounds. The influence of different inter- or intramolecular interactions on a second-order property can be qualitatively predicted if it can be known how they affect the main virtual excitations entering into that second-order property. A set of consistent approximations are introduced in order to analyze the behavior of occupied and virtual orbitais that define some experimental trends of magnetic shielding constants. This approach is applied first to study the electronic origin of methyl-β substituent effects on both 15N and 17O chemical shifts, and afterward it is applied to a couple of examples of long-range substituent effects originated in charge transfer interactions such as the conjugative effect in aromatic compounds and σ-hyperconjugative interactions in saturated multicyclic compounds. © 2009 American Chemical Society. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Pagola, G.I. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Melo, J.I. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2009 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895639_v113_n36_p9874_Contreras http://hdl.handle.net/20.500.12110/paper_10895639_v113_n36_p9874_Contreras
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Charge transfer interaction
Conjugative effect
Electronic origin
Hyperconjugative interactions
Intramolecular interactions
Magnetic shielding constant
Model system
Qualitative approach
Qualitative study
Second orders
Substituent effect
Virtual excitations
Charge transfer
Ion exchange
Sulfur compounds
Chemical shift
spellingShingle Charge transfer interaction
Conjugative effect
Electronic origin
Hyperconjugative interactions
Intramolecular interactions
Magnetic shielding constant
Model system
Qualitative approach
Qualitative study
Second orders
Substituent effect
Virtual excitations
Charge transfer
Ion exchange
Sulfur compounds
Chemical shift
Contreras, Rubén Horacio
Pagola, Gabriel Ignacio
Melo, Juan Ignacio
Qualitative study of substituent effects on NMR15N and 17O chemical shifts
topic_facet Charge transfer interaction
Conjugative effect
Electronic origin
Hyperconjugative interactions
Intramolecular interactions
Magnetic shielding constant
Model system
Qualitative approach
Qualitative study
Second orders
Substituent effect
Virtual excitations
Charge transfer
Ion exchange
Sulfur compounds
Chemical shift
description A qualitative approach to analyze the electronic origin of substituent effects on the paramagnetic part of chemical shifts is described and applied to few model systems, where its potentiality can be appreciated. The formulation of this approach is based on the following grounds. The influence of different inter- or intramolecular interactions on a second-order property can be qualitatively predicted if it can be known how they affect the main virtual excitations entering into that second-order property. A set of consistent approximations are introduced in order to analyze the behavior of occupied and virtual orbitais that define some experimental trends of magnetic shielding constants. This approach is applied first to study the electronic origin of methyl-β substituent effects on both 15N and 17O chemical shifts, and afterward it is applied to a couple of examples of long-range substituent effects originated in charge transfer interactions such as the conjugative effect in aromatic compounds and σ-hyperconjugative interactions in saturated multicyclic compounds. © 2009 American Chemical Society.
author Contreras, Rubén Horacio
Pagola, Gabriel Ignacio
Melo, Juan Ignacio
author_facet Contreras, Rubén Horacio
Pagola, Gabriel Ignacio
Melo, Juan Ignacio
author_sort Contreras, Rubén Horacio
title Qualitative study of substituent effects on NMR15N and 17O chemical shifts
title_short Qualitative study of substituent effects on NMR15N and 17O chemical shifts
title_full Qualitative study of substituent effects on NMR15N and 17O chemical shifts
title_fullStr Qualitative study of substituent effects on NMR15N and 17O chemical shifts
title_full_unstemmed Qualitative study of substituent effects on NMR15N and 17O chemical shifts
title_sort qualitative study of substituent effects on nmr15n and 17o chemical shifts
publishDate 2009
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895639_v113_n36_p9874_Contreras
http://hdl.handle.net/20.500.12110/paper_10895639_v113_n36_p9874_Contreras
work_keys_str_mv AT contrerasrubenhoracio qualitativestudyofsubstituenteffectsonnmr15nand17ochemicalshifts
AT pagolagabrielignacio qualitativestudyofsubstituenteffectsonnmr15nand17ochemicalshifts
AT melojuanignacio qualitativestudyofsubstituenteffectsonnmr15nand17ochemicalshifts
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