H-1 NMR Chemical Shifts of Cyclopropane and Cyclobutane: A Theoretical Study
Samo za registrovane korisnike
2013
Članak u časopisu (Objavljena verzija)
Metapodaci
Prikaz svih podataka o dokumentuApstrakt
This study was undertaken in order to rationalize the peculiar H-1 NMR chemical shifts of cyclopropane (delta 0.22) and cyclobutane (delta 1.98) which are shifted upfield and downfield with respect to larger cycloalkanes (delta 1.44-1.54). This is conventionally accounted for by shielding contributions arising from an aromatic-like ring current in cyclopropane, involving six electrons in the three C-C bonds, and deshielding coming from the sigma antiaromatic CC framework of cyclobutane. The shielding pattern arising from the cyclopropane and cyclobutane CC framework response to a perpendicular magnetic field was visualized as two-dimensional grid distribution of NICS values. Further insight into the origin of chemical shift values was obtained by the NCS-NBO analysis of proton shielding tensor. In the case of cyclopropane, the CC framework shielding pattern implies the existence of both delocalized and localized currents that have a dominant shielding effect on protons. The magnitude o...f C-H bonds shielding effect is significant, too. Unlike the conventional interpretation, the CC framework shields cyclobutane hydrogens, and its response to a perpendicular magnetic field is quite similar to responses of other planar sigma CC frameworks.
Izvor:
Journal of Organic Chemistry, 2013, 78, 4, 1504-1507Izdavač:
- Amer Chemical Soc, Washington
Finansiranje / projekti:
- Eksperimentalna i teorijska proučavanja reaktivnosti i biološka aktivnost stereodefinisanih tiazolidina i sintetičkih analoga (RS-MESTD-Basic Research (BR or ON)-172020)
Napomena:
- Supplementary material: http://cherry.chem.bg.ac.rs/handle/123456789/3498
DOI: 10.1021/jo3025863
ISSN: 0022-3263
PubMed: 23330566
WoS: 000315254100019
Scopus: 2-s2.0-84873955750
Kolekcije
Institucija/grupa
Hemijski fakultet / Faculty of ChemistryTY - JOUR AU - Baranac-Stojanović, Marija AU - Stojanović, Milovan PY - 2013 UR - https://cherry.chem.bg.ac.rs/handle/123456789/1604 AB - This study was undertaken in order to rationalize the peculiar H-1 NMR chemical shifts of cyclopropane (delta 0.22) and cyclobutane (delta 1.98) which are shifted upfield and downfield with respect to larger cycloalkanes (delta 1.44-1.54). This is conventionally accounted for by shielding contributions arising from an aromatic-like ring current in cyclopropane, involving six electrons in the three C-C bonds, and deshielding coming from the sigma antiaromatic CC framework of cyclobutane. The shielding pattern arising from the cyclopropane and cyclobutane CC framework response to a perpendicular magnetic field was visualized as two-dimensional grid distribution of NICS values. Further insight into the origin of chemical shift values was obtained by the NCS-NBO analysis of proton shielding tensor. In the case of cyclopropane, the CC framework shielding pattern implies the existence of both delocalized and localized currents that have a dominant shielding effect on protons. The magnitude of C-H bonds shielding effect is significant, too. Unlike the conventional interpretation, the CC framework shields cyclobutane hydrogens, and its response to a perpendicular magnetic field is quite similar to responses of other planar sigma CC frameworks. PB - Amer Chemical Soc, Washington T2 - Journal of Organic Chemistry T1 - H-1 NMR Chemical Shifts of Cyclopropane and Cyclobutane: A Theoretical Study VL - 78 IS - 4 SP - 1504 EP - 1507 DO - 10.1021/jo3025863 ER -
@article{ author = "Baranac-Stojanović, Marija and Stojanović, Milovan", year = "2013", abstract = "This study was undertaken in order to rationalize the peculiar H-1 NMR chemical shifts of cyclopropane (delta 0.22) and cyclobutane (delta 1.98) which are shifted upfield and downfield with respect to larger cycloalkanes (delta 1.44-1.54). This is conventionally accounted for by shielding contributions arising from an aromatic-like ring current in cyclopropane, involving six electrons in the three C-C bonds, and deshielding coming from the sigma antiaromatic CC framework of cyclobutane. The shielding pattern arising from the cyclopropane and cyclobutane CC framework response to a perpendicular magnetic field was visualized as two-dimensional grid distribution of NICS values. Further insight into the origin of chemical shift values was obtained by the NCS-NBO analysis of proton shielding tensor. In the case of cyclopropane, the CC framework shielding pattern implies the existence of both delocalized and localized currents that have a dominant shielding effect on protons. The magnitude of C-H bonds shielding effect is significant, too. Unlike the conventional interpretation, the CC framework shields cyclobutane hydrogens, and its response to a perpendicular magnetic field is quite similar to responses of other planar sigma CC frameworks.", publisher = "Amer Chemical Soc, Washington", journal = "Journal of Organic Chemistry", title = "H-1 NMR Chemical Shifts of Cyclopropane and Cyclobutane: A Theoretical Study", volume = "78", number = "4", pages = "1504-1507", doi = "10.1021/jo3025863" }
Baranac-Stojanović, M.,& Stojanović, M.. (2013). H-1 NMR Chemical Shifts of Cyclopropane and Cyclobutane: A Theoretical Study. in Journal of Organic Chemistry Amer Chemical Soc, Washington., 78(4), 1504-1507. https://doi.org/10.1021/jo3025863
Baranac-Stojanović M, Stojanović M. H-1 NMR Chemical Shifts of Cyclopropane and Cyclobutane: A Theoretical Study. in Journal of Organic Chemistry. 2013;78(4):1504-1507. doi:10.1021/jo3025863 .
Baranac-Stojanović, Marija, Stojanović, Milovan, "H-1 NMR Chemical Shifts of Cyclopropane and Cyclobutane: A Theoretical Study" in Journal of Organic Chemistry, 78, no. 4 (2013):1504-1507, https://doi.org/10.1021/jo3025863 . .