NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies
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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Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v754_n1-3_p1_Taurian http://hdl.handle.net/20.500.12110/paper_00222860_v754_n1-3_p1_Taurian |
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paper:paper_00222860_v754_n1-3_p1_Taurian2023-06-08T14:48:57Z NMR J(13C,13C) spin-spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies Contreras, Rubén Horacio 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. 2005 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v754_n1-3_p1_Taurian 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 Contreras, Rubén Horacio 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. |
author |
Contreras, Rubén Horacio |
author_facet |
Contreras, Rubén Horacio |
author_sort |
Contreras, Rubén Horacio |
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 |
publishDate |
2005 |
url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v754_n1-3_p1_Taurian http://hdl.handle.net/20.500.12110/paper_00222860_v754_n1-3_p1_Taurian |
work_keys_str_mv |
AT contrerasrubenhoracio nmrj13c13cspinspincouplingconstantsinpyridinecarboxaldehydesexperimentalanddftb3lypstudies |
_version_ |
1768543118513143808 |