Environmental effects on phenoxyl free radical spin densities and hyperfine couplings

2005 ◽  
Vol 730 (1-3) ◽  
pp. 251-254 ◽  
Author(s):  
Pete Wu ◽  
Patrick J. O'Malley
Keyword(s):  
Free Radical ◽  
Environmental Effects ◽  
Spin Densities ◽  
Hyperfine Couplings

ESR Studies on 205Tl Hyperfine Couplings in the Radical Cations of Tl(III)Porphyrins

1974 ◽  
Vol 29 (12) ◽  
pp. 1827-1833 ◽  
Author(s):  
Chr. Mengersen ◽  
J. Subramanian ◽  
J.-H. Fuhrhop ◽  
K. M. Smith
Keyword(s):  
Spin Density ◽  
Spin Polarization ◽  
Radical Cations ◽  
Esr Spectra ◽  
Cation Radicals ◽  
Bilinear Relation ◽  
Tetraphenyl Porphyrin ◽  
Pi Orbitals ◽  
Spin Densities ◽  
Hyperfine Couplings

The isotropic 205Tl hyperfine couplings obtained from the ESR spectra of the radical cations of Tl (III) meso tetraphenyl porphyrin (TPP), octaethyl porphyrin (OEP) and octaethyl chlorin (OEC) are reported. The radical cations were generated by electrooxidation in dichloromethane as solvent. A Karplus-Fraenkel type bilinear relation is used to interpret the 205Tl couplings, taking into account the sigma-pi spin polarization of Tl -N bonds by the spin density at the nitrogen atoms in the ligand as well as the direct pi interaction of the orbitals of Tl with the pi orbitals of the ligand. It is shown that for the cation radicals of Tl porphyrins, both these mechanisms contribute to the Tl couplings whereas for the cation radicals of Co- and Zn-porphyrins the sigma-pi polarization alone is sufficient to account for the metal hyperfine couplings. It is suggested that Tl-hyperfine couplings can be used to estimate the nitrogen spin densities of porphyrin radical systems when the nitrogen splittings are not resolved in the ESR spectra.

Analysis of the ESR Hyperfine Coupling in Mono- and Bicyclic Azine Radical Anions by Means of Calculated Spin Densities

1983 ◽  
Vol 38 (4) ◽  
pp. 415-427
Author(s):  
Michael H. Palmerand ◽  
Isobel Simpson
Keyword(s):  
Aromatic Compounds ◽  
Hyperfine Coupling ◽  
Wave Functions ◽  
Radical Anions ◽  
Spin Population ◽  
Calculated Density ◽  
Double Zeta ◽  
Statistical Variations ◽  
Spin Densities ◽  
Hyperfine Couplings

Ab initio studies of the spin density in mono- and bicyclic N hetero-aromatic compounds, and naphthalene are reported. The wave functions were constructed from both minimal and double zeta bases in all cases, and both RHF and UHF formalisms were used together with quartet annihilation. The statistical variations in correlations between spin population density and hyperfine coupling are investigated. After annihilation the MB and DZ wave functions become relatively similar, but do lead to some differences in assignment for the smaller values of aH . In general the agreement aH/aN between and calculated density is improved by two term rather than one term expressions, but there are still a number of experimental hyperfine couplings awaited.

Spin Densities in the Cyclohexadienyl Free Radical

1962 ◽  
Vol 37 (5) ◽  
pp. 1094-1096 ◽  
Author(s):  
Hanns Fischer
Keyword(s):  
Free Radical ◽  
Spin Densities

Spin Densities in the Perinaphthenyl Free Radical

1958 ◽  
Vol 28 (1) ◽  
pp. 51-53 ◽  
Author(s):  
Harden M. McConnell ◽  
Henry H. Dearman
Keyword(s):  
Free Radical ◽  
Spin Densities
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