NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies

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J(13C,13C) spin-spin couplings were measured at natural abundance in five pyridine aldehyde derivatives. Such couplings were also calculated at the DFT-B3LYP-6-311G**/EPR-III level of theory where special attention was paid to their possible stereospecific behaviors. Dielectric solvent effects were...

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Autores principales: Taurian, O.E., De Kowalewski, D.G., Pérez, J.E., Contreras, R.H.
Formato: JOUR
Materias:
Conjugative interactions
Geminal couplings
Negative hyperconjugative interactions
Scalar couplings
Stereospecificity
Aldehydes
Carbon monoxide
Conformations
Continuum mechanics
Antibonding orbitals
Pyridine aldehydes
Molecular structure
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00222860_v754_n1-3_p1_Taurian
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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_00222860_v754_n1-3_p1_Taurian2023-10-03T14:30:41Z NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies Taurian, O.E. De Kowalewski, D.G. Pérez, J.E. Contreras, R.H. Conjugative interactions Geminal couplings Negative hyperconjugative interactions Scalar couplings Stereospecificity Aldehydes Carbon monoxide Conformations Continuum mechanics Antibonding orbitals Conjugative interactions Pyridine aldehydes Molecular structure J(13C,13C) spin-spin couplings were measured at natural abundance in five pyridine aldehyde derivatives. Such couplings were also calculated at the DFT-B3LYP-6-311G**/EPR-III level of theory where special attention was paid to their possible stereospecific behaviors. Dielectric solvent effects were calculated on all four isotropic contributions to J(13C,13C) couplings using the polarization continuum model, PCM. It is observed that the inclusion of dielectric solvent effects in general leads to a better agreement between calculated and experimental couplings. 2J(13CC,13CA) couplings were observed to be sensitive to the aldehyde side-chain conformation (coupling pathway: CC-Ci-CA, where C C stands for the carbonyl-, Ci is the aromatic ipso- and CA is an adjacent aromatic-C atom). This is a positive coupling and becomes unusually large for a trans configuration between the carbonyl CO and the CC-Ci bonds. In this conformation, there is an enhancement of conjugative interactions involving the π(CO) and π(C CCi) bonding and antibonding orbitals. © 2005 Elsevier B.V. All rights reserved. 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_00222860_v754_n1-3_p1_Taurian
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Conjugative interactions
Geminal couplings
Negative hyperconjugative interactions
Scalar couplings
Stereospecificity
Aldehydes
Carbon monoxide
Conformations
Continuum mechanics
Antibonding orbitals
Conjugative interactions
Pyridine aldehydes
Molecular structure
spellingShingle Conjugative interactions
Geminal couplings
Negative hyperconjugative interactions
Scalar couplings
Stereospecificity
Aldehydes
Carbon monoxide
Conformations
Continuum mechanics
Antibonding orbitals
Conjugative interactions
Pyridine aldehydes
Molecular structure
Taurian, O.E.
De Kowalewski, D.G.
Pérez, J.E.
Contreras, R.H.
NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies
topic_facet Conjugative interactions
Geminal couplings
Negative hyperconjugative interactions
Scalar couplings
Stereospecificity
Aldehydes
Carbon monoxide
Conformations
Continuum mechanics
Antibonding orbitals
Conjugative interactions
Pyridine aldehydes
Molecular structure
description J(13C,13C) spin-spin couplings were measured at natural abundance in five pyridine aldehyde derivatives. Such couplings were also calculated at the DFT-B3LYP-6-311G**/EPR-III level of theory where special attention was paid to their possible stereospecific behaviors. Dielectric solvent effects were calculated on all four isotropic contributions to J(13C,13C) couplings using the polarization continuum model, PCM. It is observed that the inclusion of dielectric solvent effects in general leads to a better agreement between calculated and experimental couplings. 2J(13CC,13CA) couplings were observed to be sensitive to the aldehyde side-chain conformation (coupling pathway: CC-Ci-CA, where C C stands for the carbonyl-, Ci is the aromatic ipso- and CA is an adjacent aromatic-C atom). This is a positive coupling and becomes unusually large for a trans configuration between the carbonyl CO and the CC-Ci bonds. In this conformation, there is an enhancement of conjugative interactions involving the π(CO) and π(C CCi) bonding and antibonding orbitals. © 2005 Elsevier B.V. All rights reserved.
format JOUR
author Taurian, O.E.
De Kowalewski, D.G.
Pérez, J.E.
Contreras, R.H.
author_facet Taurian, O.E.
De Kowalewski, D.G.
Pérez, J.E.
Contreras, R.H.
author_sort Taurian, O.E.
title NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies
title_short NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies
title_full NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies
title_fullStr NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies
title_full_unstemmed NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies
title_sort nmr j(13c,13c) spin-spin coupling constants in pyridine-carboxaldehydes. experimental and dft-b3lyp studies
url http://hdl.handle.net/20.500.12110/paper_00222860_v754_n1-3_p1_Taurian
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