Singlet stabilization of oxazole- and isoxazolenitrene-n-oxides by radical delocalization

Ekram Hossain, Paul G. Wenthold

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Spin-flip coupled-cluster methods have been used to calculate the structures and energies of singlet and triplet electronic states of all the geometrical isomers of isoxazolyl- and oxazolylnitrene-n-oxides. At the CCSD(T)/cc-pVTZ level of theory, 2-oxazolylnitrene-n-oxide and 5-isoxazolylnitrene-n-oxide are calculated to have the smallest singlet-triplet energy splittings, at 4.7 and 6.3. kcal/mol, respectively. The results for all isomers indicate that the singlet states are most effectively stabilized by having the nitrene nitrogen adjacent to the oxygen in the ring, and being able to delocalize π-spin density onto the nitroxyl oxygen. Empirical analysis of the spin dependent stabilization finds that the extent to which singlet states are stabilized is approximately twice that found for triplet states, suggesting that radical stabilizing ability can also be applied to singlet-triplet splitting.

Original languageEnglish (US)
Pages (from-to)180-186
Number of pages7
JournalComputational and Theoretical Chemistry
Volume1020
DOIs
StatePublished - Sep 15 2013
Externally publishedYes

Fingerprint

Oxazoles
oxazole
Oxides
Stabilization
stabilization
Isomers
oxides
isomers
Oxygen
Electronic states
oxygen
atomic energy levels
Nitrogen
nitrogen
energy
rings
electronics

Keywords

  • Aromatic nitrenes
  • Coupled-cluster calculations
  • Radical stabilization
  • Singlet-triplet splittings
  • Spin flip

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Biochemistry
  • Condensed Matter Physics

Cite this

Singlet stabilization of oxazole- and isoxazolenitrene-n-oxides by radical delocalization. / Hossain, Ekram; Wenthold, Paul G.

In: Computational and Theoretical Chemistry, Vol. 1020, 15.09.2013, p. 180-186.

Research output: Contribution to journalArticle

@article{fcbf475973554ca1963bc16b580240aa,
title = "Singlet stabilization of oxazole- and isoxazolenitrene-n-oxides by radical delocalization",
abstract = "Spin-flip coupled-cluster methods have been used to calculate the structures and energies of singlet and triplet electronic states of all the geometrical isomers of isoxazolyl- and oxazolylnitrene-n-oxides. At the CCSD(T)/cc-pVTZ level of theory, 2-oxazolylnitrene-n-oxide and 5-isoxazolylnitrene-n-oxide are calculated to have the smallest singlet-triplet energy splittings, at 4.7 and 6.3. kcal/mol, respectively. The results for all isomers indicate that the singlet states are most effectively stabilized by having the nitrene nitrogen adjacent to the oxygen in the ring, and being able to delocalize π-spin density onto the nitroxyl oxygen. Empirical analysis of the spin dependent stabilization finds that the extent to which singlet states are stabilized is approximately twice that found for triplet states, suggesting that radical stabilizing ability can also be applied to singlet-triplet splitting.",
keywords = "Aromatic nitrenes, Coupled-cluster calculations, Radical stabilization, Singlet-triplet splittings, Spin flip",
author = "Ekram Hossain and Wenthold, {Paul G.}",
year = "2013",
month = "9",
day = "15",
doi = "10.1016/j.comptc.2013.07.028",
language = "English (US)",
volume = "1020",
pages = "180--186",
journal = "Computational and Theoretical Chemistry",
issn = "2210-271X",
publisher = "Elsevier BV",

}

TY - JOUR

T1 - Singlet stabilization of oxazole- and isoxazolenitrene-n-oxides by radical delocalization

AU - Hossain, Ekram

AU - Wenthold, Paul G.

PY - 2013/9/15

Y1 - 2013/9/15

N2 - Spin-flip coupled-cluster methods have been used to calculate the structures and energies of singlet and triplet electronic states of all the geometrical isomers of isoxazolyl- and oxazolylnitrene-n-oxides. At the CCSD(T)/cc-pVTZ level of theory, 2-oxazolylnitrene-n-oxide and 5-isoxazolylnitrene-n-oxide are calculated to have the smallest singlet-triplet energy splittings, at 4.7 and 6.3. kcal/mol, respectively. The results for all isomers indicate that the singlet states are most effectively stabilized by having the nitrene nitrogen adjacent to the oxygen in the ring, and being able to delocalize π-spin density onto the nitroxyl oxygen. Empirical analysis of the spin dependent stabilization finds that the extent to which singlet states are stabilized is approximately twice that found for triplet states, suggesting that radical stabilizing ability can also be applied to singlet-triplet splitting.

AB - Spin-flip coupled-cluster methods have been used to calculate the structures and energies of singlet and triplet electronic states of all the geometrical isomers of isoxazolyl- and oxazolylnitrene-n-oxides. At the CCSD(T)/cc-pVTZ level of theory, 2-oxazolylnitrene-n-oxide and 5-isoxazolylnitrene-n-oxide are calculated to have the smallest singlet-triplet energy splittings, at 4.7 and 6.3. kcal/mol, respectively. The results for all isomers indicate that the singlet states are most effectively stabilized by having the nitrene nitrogen adjacent to the oxygen in the ring, and being able to delocalize π-spin density onto the nitroxyl oxygen. Empirical analysis of the spin dependent stabilization finds that the extent to which singlet states are stabilized is approximately twice that found for triplet states, suggesting that radical stabilizing ability can also be applied to singlet-triplet splitting.

KW - Aromatic nitrenes

KW - Coupled-cluster calculations

KW - Radical stabilization

KW - Singlet-triplet splittings

KW - Spin flip

UR - http://www.scopus.com/inward/record.url?scp=84883402999&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84883402999&partnerID=8YFLogxK

U2 - 10.1016/j.comptc.2013.07.028

DO - 10.1016/j.comptc.2013.07.028

M3 - Article

AN - SCOPUS:84883402999

VL - 1020

SP - 180

EP - 186

JO - Computational and Theoretical Chemistry

JF - Computational and Theoretical Chemistry

SN - 2210-271X

ER -