Abstract:
According to the ring current model quoted in textbooks of nuclear magnetic resonance spectroscopy, the downfield chemical shifts of hydrogen nuclei in aromatic molecules is due to intense delocalized currents induced in the π-electron cloud by a magnetic field at right angles to the molecular plane. By using the Biot-Savart law, it was found that the delocalized ring currents deshield the out-of-plane component of proton shielding tensor via an essentially local mechanism taking place in the close vicinity of protons. The π ring currents over distant carbons shield the protons. π and σ electrons deshield benzene protons via different mechanisms clearly observed in plots of the shielding density function defined in the text. These results provide a novel interpretation of the phenomenology and suggest that the familiar model for interpreting chemical shifts of aromatics should be revised. © 2004 Published by Elsevier B.V.
Registro:
| Documento: |
Artículo
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| Título: | Understanding proton magnetic shielding in the benzene molecule |
| Autor: | Ferraro, M.B.; Lazzeretti, P.; Viglione, R.G.; Zanasi, R. |
| Filiación: | Departamento de Física, Fac. de Ciencias Exactas Y Naturales, Pab. I, (1428) Buenos Aires, Argentina
Dipartimento di Chimica, Dell'Univ. Studi Modena Reggio E., Via Campi 183, 41100 Modena, Italy
Dipartimento di Chimica, Dell'Univ. degli Studi di Salerno, via S. Allende, 84081 Baronissi (SA), Italy
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| Palabras clave: | aromatic compound; benzene; carbon; proton; article; density functional theory; electric current; electron; model; molecular mechanics; molecule; phenomenology; proton nuclear magnetic resonance |
| Año: | 2004
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| Volumen: | 390
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| Número: | 1-3
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| Página de inicio: | 268
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| Página de fin: | 271
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| DOI: |
http://dx.doi.org/10.1016/j.cplett.2004.04.022 |
| Título revista: | Chemical Physics Letters
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| Título revista abreviado: | Chem. Phys. Lett.
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| ISSN: | 00092614
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| CODEN: | CHPLB
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| CAS: | benzene, 71-43-2; carbon, 7440-44-0; proton, 12408-02-5, 12586-59-3
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| Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00092614_v390_n1-3_p268_Ferraro |
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Citas:
---------- APA ----------
Ferraro, M.B., Lazzeretti, P., Viglione, R.G. & Zanasi, R.
(2004)
. Understanding proton magnetic shielding in the benzene molecule. Chemical Physics Letters, 390(1-3), 268-271.
http://dx.doi.org/10.1016/j.cplett.2004.04.022---------- CHICAGO ----------
Ferraro, M.B., Lazzeretti, P., Viglione, R.G., Zanasi, R.
"Understanding proton magnetic shielding in the benzene molecule"
. Chemical Physics Letters 390, no. 1-3
(2004) : 268-271.
http://dx.doi.org/10.1016/j.cplett.2004.04.022---------- MLA ----------
Ferraro, M.B., Lazzeretti, P., Viglione, R.G., Zanasi, R.
"Understanding proton magnetic shielding in the benzene molecule"
. Chemical Physics Letters, vol. 390, no. 1-3, 2004, pp. 268-271.
http://dx.doi.org/10.1016/j.cplett.2004.04.022---------- VANCOUVER ----------
Ferraro, M.B., Lazzeretti, P., Viglione, R.G., Zanasi, R. Understanding proton magnetic shielding in the benzene molecule. Chem. Phys. Lett. 2004;390(1-3):268-271.
http://dx.doi.org/10.1016/j.cplett.2004.04.022
