Is the Conventional Interpretation of the Anisotropic Effects of C?C Double Bonds and Aromatic Rings in NMR Spectra in Terms of the p-Electron Shielding/Deshielding Contributions Correct?
Abstract
Based on the nucleus-independent chemical shift (NICS) concept, isotropic magnetic shielding values have been computed along the three Cartesian axes for ethene, cyclobutadiene, benzene, naphthalene, and benzocyclobutadiene, starting from the molecular/ring center up to 10 angstrom away. These through-space NMR spectroscopic shielding (TSNMRS) values, which reflect the anisotropic effects, have been broken down into contributions from localized- and canonical molecular orbitals (LMOs and CMOs); these contributions revealed that the proton NMR spectroscopic chemical shifts of nuclei that are spatially close to the C?C double bond or the aromatic ring should not be explained in terms of the conventionally accepted p-electron shielding/deshielding effects. In fact, these effects followed the predictions only for the antiaromatic cyclobutadiene ring.
Keywords:
ab initio calculations / anisotropic effects / NMR spectroscopy / nucleus-independent chemical shift / pi interactionsSource:
Chemistry. A European Journal, 2012, 18, 1, 370-376Publisher:
- Wiley-Blackwell, Malden
Funding / projects:
- Deutscher Akademischer Austauschdienst (DAAD) [504 252 70]
- Ministry of Science of the Republic of Serbia
DOI: 10.1002/chem.201101882
ISSN: 0947-6539
PubMed: 22135110
WoS: 000298547800044
Scopus: 2-s2.0-84555196522
Collections
Institution/Community
Hemijski fakultet / Faculty of ChemistryTY - JOUR AU - Baranac-Stojanović, Marija AU - Koch, Andreas AU - Kleinpeter, Erich PY - 2012 UR - https://cherry.chem.bg.ac.rs/handle/123456789/1236 AB - Based on the nucleus-independent chemical shift (NICS) concept, isotropic magnetic shielding values have been computed along the three Cartesian axes for ethene, cyclobutadiene, benzene, naphthalene, and benzocyclobutadiene, starting from the molecular/ring center up to 10 angstrom away. These through-space NMR spectroscopic shielding (TSNMRS) values, which reflect the anisotropic effects, have been broken down into contributions from localized- and canonical molecular orbitals (LMOs and CMOs); these contributions revealed that the proton NMR spectroscopic chemical shifts of nuclei that are spatially close to the C?C double bond or the aromatic ring should not be explained in terms of the conventionally accepted p-electron shielding/deshielding effects. In fact, these effects followed the predictions only for the antiaromatic cyclobutadiene ring. PB - Wiley-Blackwell, Malden T2 - Chemistry. A European Journal T1 - Is the Conventional Interpretation of the Anisotropic Effects of C?C Double Bonds and Aromatic Rings in NMR Spectra in Terms of the p-Electron Shielding/Deshielding Contributions Correct? VL - 18 IS - 1 SP - 370 EP - 376 DO - 10.1002/chem.201101882 ER -
@article{ author = "Baranac-Stojanović, Marija and Koch, Andreas and Kleinpeter, Erich", year = "2012", abstract = "Based on the nucleus-independent chemical shift (NICS) concept, isotropic magnetic shielding values have been computed along the three Cartesian axes for ethene, cyclobutadiene, benzene, naphthalene, and benzocyclobutadiene, starting from the molecular/ring center up to 10 angstrom away. These through-space NMR spectroscopic shielding (TSNMRS) values, which reflect the anisotropic effects, have been broken down into contributions from localized- and canonical molecular orbitals (LMOs and CMOs); these contributions revealed that the proton NMR spectroscopic chemical shifts of nuclei that are spatially close to the C?C double bond or the aromatic ring should not be explained in terms of the conventionally accepted p-electron shielding/deshielding effects. In fact, these effects followed the predictions only for the antiaromatic cyclobutadiene ring.", publisher = "Wiley-Blackwell, Malden", journal = "Chemistry. A European Journal", title = "Is the Conventional Interpretation of the Anisotropic Effects of C?C Double Bonds and Aromatic Rings in NMR Spectra in Terms of the p-Electron Shielding/Deshielding Contributions Correct?", volume = "18", number = "1", pages = "370-376", doi = "10.1002/chem.201101882" }
Baranac-Stojanović, M., Koch, A.,& Kleinpeter, E.. (2012). Is the Conventional Interpretation of the Anisotropic Effects of C?C Double Bonds and Aromatic Rings in NMR Spectra in Terms of the p-Electron Shielding/Deshielding Contributions Correct?. in Chemistry. A European Journal Wiley-Blackwell, Malden., 18(1), 370-376. https://doi.org/10.1002/chem.201101882
Baranac-Stojanović M, Koch A, Kleinpeter E. Is the Conventional Interpretation of the Anisotropic Effects of C?C Double Bonds and Aromatic Rings in NMR Spectra in Terms of the p-Electron Shielding/Deshielding Contributions Correct?. in Chemistry. A European Journal. 2012;18(1):370-376. doi:10.1002/chem.201101882 .
Baranac-Stojanović, Marija, Koch, Andreas, Kleinpeter, Erich, "Is the Conventional Interpretation of the Anisotropic Effects of C?C Double Bonds and Aromatic Rings in NMR Spectra in Terms of the p-Electron Shielding/Deshielding Contributions Correct?" in Chemistry. A European Journal, 18, no. 1 (2012):370-376, https://doi.org/10.1002/chem.201101882 . .