Aromaticity and Stability of Azaborines
Abstract
The influence of the relative boron and nitrogen positions on aromaticity of the three isomeric 1,2-, 1,3-, and 1,4-azaborines has been investigated by computing the extra cyclic resonance energy, NICS(0)(pi zz) index and by visualizing the pi-electron (de) shielding pattern as a response of the pi system to a perpendicular magnetic field. The origin of the known stability trend, in which the 1,2-/1,3-isomer is the most/least stable, was examined by using an isomerization energy decomposition analysis. The 1,3-arrangement of B and N atoms creates a charge separation in the pi-electron system, which was found to be responsible for the lowest stability of 1,3-azaborine. This charge separation can, in turn, be considered as a driving force for the strongest cyclic pi-electron delocalization, making this same isomer the most aromatic. Despite the well-known fact that the B-N bond attenuates electron delocalization due to large electronegativity difference between the atoms, the 1,4-B, N re...lationship reduces aromaticity to a greater extent by making the pi-electron delocalization more one-directional (from N to B) than cyclic. Thus, 1,4-azaborine was found to be the least aromatic. Its lower stability with respect to the 1,2-isomer was explained by the larger exchange repulsion.
Keywords:
aromaticity / conjugation / density functional calculations / heterocycles / bond theorySource:
Chemistry. A European Journal, 2014, 20, 50, 16558-16565Publisher:
- Wiley-V C H Verlag Gmbh, Weinheim
Funding / projects:
- Experimental and theoretical study of reactivity and biological activity of stereodefined thiazolidines and their synthetic analogues (RS-MESTD-Basic Research (BR or ON)-172020)
Note:
- Supplementary material: http://cherry.chem.bg.ac.rs/handle/123456789/3678
DOI: 10.1002/chem.201402851
ISSN: 0947-6539
PubMed: 25331155
WoS: 000346055800021
Scopus: 2-s2.0-84929998689
Collections
Institution/Community
Hemijski fakultet / Faculty of ChemistryTY - JOUR AU - Baranac-Stojanović, Marija PY - 2014 UR - https://cherry.chem.bg.ac.rs/handle/123456789/1886 AB - The influence of the relative boron and nitrogen positions on aromaticity of the three isomeric 1,2-, 1,3-, and 1,4-azaborines has been investigated by computing the extra cyclic resonance energy, NICS(0)(pi zz) index and by visualizing the pi-electron (de) shielding pattern as a response of the pi system to a perpendicular magnetic field. The origin of the known stability trend, in which the 1,2-/1,3-isomer is the most/least stable, was examined by using an isomerization energy decomposition analysis. The 1,3-arrangement of B and N atoms creates a charge separation in the pi-electron system, which was found to be responsible for the lowest stability of 1,3-azaborine. This charge separation can, in turn, be considered as a driving force for the strongest cyclic pi-electron delocalization, making this same isomer the most aromatic. Despite the well-known fact that the B-N bond attenuates electron delocalization due to large electronegativity difference between the atoms, the 1,4-B, N relationship reduces aromaticity to a greater extent by making the pi-electron delocalization more one-directional (from N to B) than cyclic. Thus, 1,4-azaborine was found to be the least aromatic. Its lower stability with respect to the 1,2-isomer was explained by the larger exchange repulsion. PB - Wiley-V C H Verlag Gmbh, Weinheim T2 - Chemistry. A European Journal T1 - Aromaticity and Stability of Azaborines VL - 20 IS - 50 SP - 16558 EP - 16565 DO - 10.1002/chem.201402851 ER -
@article{ author = "Baranac-Stojanović, Marija", year = "2014", abstract = "The influence of the relative boron and nitrogen positions on aromaticity of the three isomeric 1,2-, 1,3-, and 1,4-azaborines has been investigated by computing the extra cyclic resonance energy, NICS(0)(pi zz) index and by visualizing the pi-electron (de) shielding pattern as a response of the pi system to a perpendicular magnetic field. The origin of the known stability trend, in which the 1,2-/1,3-isomer is the most/least stable, was examined by using an isomerization energy decomposition analysis. The 1,3-arrangement of B and N atoms creates a charge separation in the pi-electron system, which was found to be responsible for the lowest stability of 1,3-azaborine. This charge separation can, in turn, be considered as a driving force for the strongest cyclic pi-electron delocalization, making this same isomer the most aromatic. Despite the well-known fact that the B-N bond attenuates electron delocalization due to large electronegativity difference between the atoms, the 1,4-B, N relationship reduces aromaticity to a greater extent by making the pi-electron delocalization more one-directional (from N to B) than cyclic. Thus, 1,4-azaborine was found to be the least aromatic. Its lower stability with respect to the 1,2-isomer was explained by the larger exchange repulsion.", publisher = "Wiley-V C H Verlag Gmbh, Weinheim", journal = "Chemistry. A European Journal", title = "Aromaticity and Stability of Azaborines", volume = "20", number = "50", pages = "16558-16565", doi = "10.1002/chem.201402851" }
Baranac-Stojanović, M.. (2014). Aromaticity and Stability of Azaborines. in Chemistry. A European Journal Wiley-V C H Verlag Gmbh, Weinheim., 20(50), 16558-16565. https://doi.org/10.1002/chem.201402851
Baranac-Stojanović M. Aromaticity and Stability of Azaborines. in Chemistry. A European Journal. 2014;20(50):16558-16565. doi:10.1002/chem.201402851 .
Baranac-Stojanović, Marija, "Aromaticity and Stability of Azaborines" in Chemistry. A European Journal, 20, no. 50 (2014):16558-16565, https://doi.org/10.1002/chem.201402851 . .