Vibrational contributions to vicinal proton-proton coupling constants3JHH
Vibrational contributions to the 3JHH couplings of six mono- and five 1,1-di-substituted ethanes, three mono-substituted cyclohexanes, three norbornane-type molecules, and 11 three-membered rings have been calculated at the DFT/B3LYP level for the Fermi contact term using a moderate sized basis set....
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todo:paper_00268976_v108_n5_p583_Esteban2023-10-03T14:37:17Z Vibrational contributions to vicinal proton-proton coupling constants3JHH Esteban, A.L. Díez, E. Galache, M.P. San Fabián, J. Casanueva, J. Contreras, R.H. DFT/B3LYP Numerical precision Vibrational contributions Vicinal coupling constants Accurate prediction Basis sets Computational precision Correlation coefficient Data sets Equilibrium configuration Equilibrium geometries Fermi contact term Molecular geometries Norbornane Normal coordinate Numerical precision Proton coupling Second derivatives Standard deviation Three-membered rings Vibrational contributions Vicinal coupling constants Complexation Protons Couplings Vibrational contributions to the 3JHH couplings of six mono- and five 1,1-di-substituted ethanes, three mono-substituted cyclohexanes, three norbornane-type molecules, and 11 three-membered rings have been calculated at the DFT/B3LYP level for the Fermi contact term using a moderate sized basis set. When, for a data set of 70 couplings, the sums of the values for the equilibrium configurations Je and the respective vibrational contributions J300vib at 300K are multiplied by a factor of 0.8485, the corresponding predicted couplings Jpre are in good agreement with the experimental couplings Jexp with a standard deviation σ of 0.18 Hz. The same σ results when J pre values are obtained by multiplying the Je values by 0.9016. However, the vibrational contributions must be taken into account, together with the Je values, in order to achieve a procedure for a reliable and accurate prediction of 3JHH couplings since, globally, J300vib contributions amount to about 7% of the Je values and the correlation coefficient between J 300vib and Je is only 0.68 with a σ deviation of 0.20. The first and diagonal second derivatives of J with respect to each normal coordinate Qk, required to estimate the vibrational contributions, have been obtained from six Jk values computed for molecular geometries positively (+δQk) and negatively (-δQk) displaced from the equilibrium geometry along the normal coordinate Qk and using for δ the values 0.01, 0.05 and 0.10. The computational precision of the results obtained when using one, two and three δ values is analysed. © 2010 Taylor & Francis. 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_00268976_v108_n5_p583_Esteban |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
DFT/B3LYP Numerical precision Vibrational contributions Vicinal coupling constants Accurate prediction Basis sets Computational precision Correlation coefficient Data sets Equilibrium configuration Equilibrium geometries Fermi contact term Molecular geometries Norbornane Normal coordinate Numerical precision Proton coupling Second derivatives Standard deviation Three-membered rings Vibrational contributions Vicinal coupling constants Complexation Protons Couplings |
| spellingShingle |
DFT/B3LYP Numerical precision Vibrational contributions Vicinal coupling constants Accurate prediction Basis sets Computational precision Correlation coefficient Data sets Equilibrium configuration Equilibrium geometries Fermi contact term Molecular geometries Norbornane Normal coordinate Numerical precision Proton coupling Second derivatives Standard deviation Three-membered rings Vibrational contributions Vicinal coupling constants Complexation Protons Couplings Esteban, A.L. Díez, E. Galache, M.P. San Fabián, J. Casanueva, J. Contreras, R.H. Vibrational contributions to vicinal proton-proton coupling constants3JHH |
| topic_facet |
DFT/B3LYP Numerical precision Vibrational contributions Vicinal coupling constants Accurate prediction Basis sets Computational precision Correlation coefficient Data sets Equilibrium configuration Equilibrium geometries Fermi contact term Molecular geometries Norbornane Normal coordinate Numerical precision Proton coupling Second derivatives Standard deviation Three-membered rings Vibrational contributions Vicinal coupling constants Complexation Protons Couplings |
| description |
Vibrational contributions to the 3JHH couplings of six mono- and five 1,1-di-substituted ethanes, three mono-substituted cyclohexanes, three norbornane-type molecules, and 11 three-membered rings have been calculated at the DFT/B3LYP level for the Fermi contact term using a moderate sized basis set. When, for a data set of 70 couplings, the sums of the values for the equilibrium configurations Je and the respective vibrational contributions J300vib at 300K are multiplied by a factor of 0.8485, the corresponding predicted couplings Jpre are in good agreement with the experimental couplings Jexp with a standard deviation σ of 0.18 Hz. The same σ results when J pre values are obtained by multiplying the Je values by 0.9016. However, the vibrational contributions must be taken into account, together with the Je values, in order to achieve a procedure for a reliable and accurate prediction of 3JHH couplings since, globally, J300vib contributions amount to about 7% of the Je values and the correlation coefficient between J 300vib and Je is only 0.68 with a σ deviation of 0.20. The first and diagonal second derivatives of J with respect to each normal coordinate Qk, required to estimate the vibrational contributions, have been obtained from six Jk values computed for molecular geometries positively (+δQk) and negatively (-δQk) displaced from the equilibrium geometry along the normal coordinate Qk and using for δ the values 0.01, 0.05 and 0.10. The computational precision of the results obtained when using one, two and three δ values is analysed. © 2010 Taylor & Francis. |
| format |
JOUR |
| author |
Esteban, A.L. Díez, E. Galache, M.P. San Fabián, J. Casanueva, J. Contreras, R.H. |
| author_facet |
Esteban, A.L. Díez, E. Galache, M.P. San Fabián, J. Casanueva, J. Contreras, R.H. |
| author_sort |
Esteban, A.L. |
| title |
Vibrational contributions to vicinal proton-proton coupling constants3JHH |
| title_short |
Vibrational contributions to vicinal proton-proton coupling constants3JHH |
| title_full |
Vibrational contributions to vicinal proton-proton coupling constants3JHH |
| title_fullStr |
Vibrational contributions to vicinal proton-proton coupling constants3JHH |
| title_full_unstemmed |
Vibrational contributions to vicinal proton-proton coupling constants3JHH |
| title_sort |
vibrational contributions to vicinal proton-proton coupling constants3jhh |
| url |
http://hdl.handle.net/20.500.12110/paper_00268976_v108_n5_p583_Esteban |
| work_keys_str_mv |
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