Abstract
We have measured the isotropic and anisotropic hyperfine splittings for di-tert-butyl nitroxide (DTBN) and 2,2,6,6-tetramethylpiperidine N-oxyl (TMPN) perturbed by molecular complex formation, by hydrogen bonding, and by solvent effects in aprotic solvents. We use these measurements to obtain the σ-π interaction parameters for a Karplus-Fraenkel equation (a1 = Q11 iρiπ + Qjj iρj π) which relates the 14N and 17O isotropic hyperfine splittings to the spin density in the nitroxide N-O π-electron system; QNN N = 23.9 ± 1.0 G, QOO N = 3.6 ± 0.4 G, QOO O = 31.7 ± 0.7 G, and QNN O = 4.7 ± 0.5 G. In addition for protonated nitroxides QOO N = 13.2 ± 0.3 G. The values of QNN N for TMPN and DTBN are identical and discussion of the angle dependence of the parameter suggests that the radicals in solution do not differ with respect to planarity at nitrogen.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1313-1321 |
| Number of pages | 9 |
| Journal | Journal of Physical Chemistry |
| Volume | 78 |
| Issue number | 13 |
| DOIs | |
| State | Published - Jan 1 1974 |
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ASJC Scopus subject areas
- Engineering(all)
- Physical and Theoretical Chemistry
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Nitrogen-14 and oxygen-17 hyperfine interactions in perturbed nitroxides. / Cohen, Allan H.; Hoffman, Brian M.
In: Journal of Physical Chemistry, Vol. 78, No. 13, 01.01.1974, p. 1313-1321.Research output: Contribution to journal › Article
TY - JOUR
T1 - Nitrogen-14 and oxygen-17 hyperfine interactions in perturbed nitroxides
AU - Cohen, Allan H.
AU - Hoffman, Brian M
PY - 1974/1/1
Y1 - 1974/1/1
N2 - We have measured the isotropic and anisotropic hyperfine splittings for di-tert-butyl nitroxide (DTBN) and 2,2,6,6-tetramethylpiperidine N-oxyl (TMPN) perturbed by molecular complex formation, by hydrogen bonding, and by solvent effects in aprotic solvents. We use these measurements to obtain the σ-π interaction parameters for a Karplus-Fraenkel equation (a1 = Q11 iρiπ + Qjj iρj π) which relates the 14N and 17O isotropic hyperfine splittings to the spin density in the nitroxide N-O π-electron system; QNN N = 23.9 ± 1.0 G, QOO N = 3.6 ± 0.4 G, QOO O = 31.7 ± 0.7 G, and QNN O = 4.7 ± 0.5 G. In addition for protonated nitroxides QOO N = 13.2 ± 0.3 G. The values of QNN N for TMPN and DTBN are identical and discussion of the angle dependence of the parameter suggests that the radicals in solution do not differ with respect to planarity at nitrogen.
AB - We have measured the isotropic and anisotropic hyperfine splittings for di-tert-butyl nitroxide (DTBN) and 2,2,6,6-tetramethylpiperidine N-oxyl (TMPN) perturbed by molecular complex formation, by hydrogen bonding, and by solvent effects in aprotic solvents. We use these measurements to obtain the σ-π interaction parameters for a Karplus-Fraenkel equation (a1 = Q11 iρiπ + Qjj iρj π) which relates the 14N and 17O isotropic hyperfine splittings to the spin density in the nitroxide N-O π-electron system; QNN N = 23.9 ± 1.0 G, QOO N = 3.6 ± 0.4 G, QOO O = 31.7 ± 0.7 G, and QNN O = 4.7 ± 0.5 G. In addition for protonated nitroxides QOO N = 13.2 ± 0.3 G. The values of QNN N for TMPN and DTBN are identical and discussion of the angle dependence of the parameter suggests that the radicals in solution do not differ with respect to planarity at nitrogen.
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U2 - 10.1021/j100606a014
DO - 10.1021/j100606a014
M3 - Article
AN - SCOPUS:0001522337
VL - 78
SP - 1313
EP - 1321
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
SN - 0022-3654
IS - 13
ER -