Heterocyclic free radicals. Part VI. Substituent effects on the distribution of the spin density in 10-arylphenoxazine and 10-arylphenothiazine cation radicals

1976 ◽  
pp. 114 ◽  
Author(s):  
David Clarke ◽  
Bruce C. Gilbert ◽  
Peter Hanson
Keyword(s):  
Free Radicals ◽  
Spin Density ◽  
Substituent Effects ◽  
Cation Radicals

Substituent effects on the formation of aminocarboxy-type capto-dative free radicals

1983 ◽  
Vol 48 (18) ◽  
pp. 2989-2994 ◽  
Author(s):  
Richard J. Himmelsbach ◽  
Anthony D. Barone ◽  
Don L. Kleyer ◽  
Tad H. Koch
Keyword(s):  
Free Radicals ◽  
Substituent Effects

Spin Density of the Nitroxide Free Radicals 4.OL and 4.OXO 2,2,6,6 Tetramethyl Piperidyl 1-OXYL: Tanol and Tano

1991 ◽  
pp. 371-384 ◽  
Author(s):  
D. Bordeaux ◽  
J. X. Boucherie ◽  
B. Delley ◽  
B. Gillon ◽  
E. Ressouche ◽  
...  
Keyword(s):  
Free Radicals ◽  
Spin Density

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.

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