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?
- 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.
| Author details: | Marija Baranac-StojanovicORCiD, Andreas KochORCiDGND, Erich KleinpeterORCiDGND |
|---|---|
| DOI: | https://doi.org/10.1002/chem.201101882 |
| ISSN: | 0947-6539 |
| Title of parent work (English): | Chemistry - a European journal |
| Publisher: | Wiley-Blackwell |
| Place of publishing: | Malden |
| Publication type: | Article |
| Language: | English |
| Year of first publication: | 2012 |
| Publication year: | 2012 |
| Release date: | 2017/03/26 |
| Tag: | NMR spectroscopy; ab initio calculations; anisotropic effects; nucleus-independent chemical shift; pi interactions |
| Volume: | 18 |
| Issue: | 1 |
| Number of pages: | 7 |
| First page: | 370 |
| Last Page: | 376 |
| Funding institution: | Ministry of Science of the Republic of Serbia; Deutscher Akademischer Austauschdienst (DAAD) [ID: 504 252 70] |
| Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie |
| Peer review: | Referiert |
