Karplus equation for3JHH spin-spin couplings with unusual3J(180°) < 3J(0°) relationship

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Vicinal 3JHH coupling constants for monosubstituted ethane molecules present the unusual relationship 3JHH (180°) < 3JHH (180°) when the substituent contains bonding and antibonding orbitals with strong hyperconjugative interactions involving bond and antibond orbitals of the ethane fragment....

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Autor principal: Contreras, Rubén Horacio
Publicado: 2008
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15499618_v4_n9_p1494_Contreras
http://hdl.handle.net/20.500.12110/paper_15499618_v4_n9_p1494_Contreras
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_15499618_v4_n9_p1494_Contreras
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spelling paper:paper_15499618_v4_n9_p1494_Contreras2023-06-08T16:21:28Z Karplus equation for3JHH spin-spin couplings with unusual3J(180°) < 3J(0°) relationship Contreras, Rubén Horacio Vicinal 3JHH coupling constants for monosubstituted ethane molecules present the unusual relationship 3JHH (180°) < 3JHH (180°) when the substituent contains bonding and antibonding orbitals with strong hyperconjugative interactions involving bond and antibond orbitals of the ethane fragment. This anomalous behavior is studied as a function of the substituent rotation for three model systems (propanal, thiopropanal, and 1-butene) at the B3LYP/TZVP level. The consistency of this level of theory to study this problem is previously established using different ab initio methods and larger basis sets. The origin of the unusual 3JHH(180°) - 3JHH(180°) relationship is attributed to simultaneous σ/π hyperconjugative interactions σC α-Hα → π*C -c=x, and σCα-Cβ → π*Cc-x. These interactions depend on the substituent rotation and their effects are different for 3J HH(180°) than for 3JHH(180°). The modelization carried out shows an increase of those effects as the substituent changes from weaker (CH=CH2) to stronger (CH=S) electron acceptor π*C=X. © 2008 American Chemical Society. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2008 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15499618_v4_n9_p1494_Contreras http://hdl.handle.net/20.500.12110/paper_15499618_v4_n9_p1494_Contreras
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description Vicinal 3JHH coupling constants for monosubstituted ethane molecules present the unusual relationship 3JHH (180°) < 3JHH (180°) when the substituent contains bonding and antibonding orbitals with strong hyperconjugative interactions involving bond and antibond orbitals of the ethane fragment. This anomalous behavior is studied as a function of the substituent rotation for three model systems (propanal, thiopropanal, and 1-butene) at the B3LYP/TZVP level. The consistency of this level of theory to study this problem is previously established using different ab initio methods and larger basis sets. The origin of the unusual 3JHH(180°) - 3JHH(180°) relationship is attributed to simultaneous σ/π hyperconjugative interactions σC α-Hα → π*C -c=x, and σCα-Cβ → π*Cc-x. These interactions depend on the substituent rotation and their effects are different for 3J HH(180°) than for 3JHH(180°). The modelization carried out shows an increase of those effects as the substituent changes from weaker (CH=CH2) to stronger (CH=S) electron acceptor π*C=X. © 2008 American Chemical Society.
author Contreras, Rubén Horacio
spellingShingle Contreras, Rubén Horacio
Karplus equation for3JHH spin-spin couplings with unusual3J(180°) < 3J(0°) relationship
author_facet Contreras, Rubén Horacio
author_sort Contreras, Rubén Horacio
title Karplus equation for3JHH spin-spin couplings with unusual3J(180°) < 3J(0°) relationship
title_short Karplus equation for3JHH spin-spin couplings with unusual3J(180°) < 3J(0°) relationship
title_full Karplus equation for3JHH spin-spin couplings with unusual3J(180°) < 3J(0°) relationship
title_fullStr Karplus equation for3JHH spin-spin couplings with unusual3J(180°) < 3J(0°) relationship
title_full_unstemmed Karplus equation for3JHH spin-spin couplings with unusual3J(180°) < 3J(0°) relationship
title_sort karplus equation for3jhh spin-spin couplings with unusual3j(180°) < 3j(0°) relationship
publishDate 2008
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15499618_v4_n9_p1494_Contreras
http://hdl.handle.net/20.500.12110/paper_15499618_v4_n9_p1494_Contreras
work_keys_str_mv AT contrerasrubenhoracio karplusequationfor3jhhspinspincouplingswithunusual3j180lt3j0relationship
_version_ 1768543293102096384

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