ESR study of the conformation of nitroxide free radicals

A. Rockenbauer, S. A. Abdel-Monem, G. Móger, L. Sümegi

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

A series of N-alkyl and N-alkyl-aryl free radicals with the structure {A figure is presented} was synthesized and the samples were investigated by ESR spectroscopy. The restricted rotation of the N-alkyl group is characterized by the deviation of the β hydrogen coupling constant of the N-alkyl group from that of the freely rotating N-methyl group: R = aH β/aH CH3 . Correlations were found between the R restriction parameter and the geometric size of the X,Y and Z groups. For methine group CHYZ the R parameter was found to decrease with the size of the X group and increase with the relative magnitude of Y group compared to Z. If X is a phenyl group, its ortho substitution exerts an orienting effect on the N-alkyl group. For the methylene group CH2Y the R factor decreases with the size of the Y group. The trends observed were applied to examine the validity of the different theoretical models described in the literature in interpreting the restricted rotation of N-alkyl groups.

Original languageEnglish
Pages (from-to)169-176
Number of pages8
JournalJournal of Molecular Structure
Volume46
Issue numberC
DOIs
Publication statusPublished - 1978

Fingerprint

Free radicals
free radicals
Free Radicals
Paramagnetic resonance
Conformations
R Factors
Hydrogen
Spectrum Analysis
Substitution reactions
Theoretical Models
Spectroscopy
nitroxyl
methylene
constrictions
substitutes
deviation
trends

ASJC Scopus subject areas

  • Structural Biology
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Materials Science (miscellaneous)
  • Atomic and Molecular Physics, and Optics

Cite this

ESR study of the conformation of nitroxide free radicals. / Rockenbauer, A.; Abdel-Monem, S. A.; Móger, G.; Sümegi, L.

In: Journal of Molecular Structure, Vol. 46, No. C, 1978, p. 169-176.

Research output: Contribution to journalArticle

Rockenbauer, A. ; Abdel-Monem, S. A. ; Móger, G. ; Sümegi, L. / ESR study of the conformation of nitroxide free radicals. In: Journal of Molecular Structure. 1978 ; Vol. 46, No. C. pp. 169-176.
@article{ab76034e9d2e436abc496a98ae03c16f,
title = "ESR study of the conformation of nitroxide free radicals",
abstract = "A series of N-alkyl and N-alkyl-aryl free radicals with the structure {A figure is presented} was synthesized and the samples were investigated by ESR spectroscopy. The restricted rotation of the N-alkyl group is characterized by the deviation of the β hydrogen coupling constant of the N-alkyl group from that of the freely rotating N-methyl group: R = aH β/aH CH3 . Correlations were found between the R restriction parameter and the geometric size of the X,Y and Z groups. For methine group CHYZ the R parameter was found to decrease with the size of the X group and increase with the relative magnitude of Y group compared to Z. If X is a phenyl group, its ortho substitution exerts an orienting effect on the N-alkyl group. For the methylene group CH2Y the R factor decreases with the size of the Y group. The trends observed were applied to examine the validity of the different theoretical models described in the literature in interpreting the restricted rotation of N-alkyl groups.",
author = "A. Rockenbauer and Abdel-Monem, {S. A.} and G. M{\'o}ger and L. S{\"u}megi",
year = "1978",
doi = "10.1016/0022-2860(78)87139-7",
language = "English",
volume = "46",
pages = "169--176",
journal = "Journal of Molecular Structure",
issn = "0022-2860",
publisher = "Elsevier",
number = "C",

}

TY - JOUR

T1 - ESR study of the conformation of nitroxide free radicals

AU - Rockenbauer, A.

AU - Abdel-Monem, S. A.

AU - Móger, G.

AU - Sümegi, L.

PY - 1978

Y1 - 1978

N2 - A series of N-alkyl and N-alkyl-aryl free radicals with the structure {A figure is presented} was synthesized and the samples were investigated by ESR spectroscopy. The restricted rotation of the N-alkyl group is characterized by the deviation of the β hydrogen coupling constant of the N-alkyl group from that of the freely rotating N-methyl group: R = aH β/aH CH3 . Correlations were found between the R restriction parameter and the geometric size of the X,Y and Z groups. For methine group CHYZ the R parameter was found to decrease with the size of the X group and increase with the relative magnitude of Y group compared to Z. If X is a phenyl group, its ortho substitution exerts an orienting effect on the N-alkyl group. For the methylene group CH2Y the R factor decreases with the size of the Y group. The trends observed were applied to examine the validity of the different theoretical models described in the literature in interpreting the restricted rotation of N-alkyl groups.

AB - A series of N-alkyl and N-alkyl-aryl free radicals with the structure {A figure is presented} was synthesized and the samples were investigated by ESR spectroscopy. The restricted rotation of the N-alkyl group is characterized by the deviation of the β hydrogen coupling constant of the N-alkyl group from that of the freely rotating N-methyl group: R = aH β/aH CH3 . Correlations were found between the R restriction parameter and the geometric size of the X,Y and Z groups. For methine group CHYZ the R parameter was found to decrease with the size of the X group and increase with the relative magnitude of Y group compared to Z. If X is a phenyl group, its ortho substitution exerts an orienting effect on the N-alkyl group. For the methylene group CH2Y the R factor decreases with the size of the Y group. The trends observed were applied to examine the validity of the different theoretical models described in the literature in interpreting the restricted rotation of N-alkyl groups.

UR - http://www.scopus.com/inward/record.url?scp=0343214134&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0343214134&partnerID=8YFLogxK

U2 - 10.1016/0022-2860(78)87139-7

DO - 10.1016/0022-2860(78)87139-7

M3 - Article

AN - SCOPUS:0343214134

VL - 46

SP - 169

EP - 176

JO - Journal of Molecular Structure

JF - Journal of Molecular Structure

SN - 0022-2860

IS - C

ER -