Semiempirical molecular orbital calculations of anisotropic1H,13C and19F hyperfine coupling constants in hydrocarbon and fluorocarbon radicals

1981 ◽  
Vol 42 (1) ◽  
pp. 153-164 ◽  
Author(s):  
Michael Barfield ◽  
Abdulla S. Babaqi ◽  
David M. Doddrell ◽  
Hans P.W. Gottlieb
Keyword(s):  
Molecular Orbital ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Molecular Orbital Calculations ◽  
Hyperfine Coupling Constants ◽  
Semiempirical Molecular Orbital

E.P.R. studies of the anions of some peri-alkylnaphthalenes

1972 ◽  
Vol 25 (11) ◽  
pp. 2353 ◽  
Author(s):  
RFC Claridge ◽  
BM Peake
Keyword(s):  
Electron Spin Resonance ◽  
Molecular Orbital ◽  
Electron Spin ◽  
Hyperfine Coupling ◽  
Inductive Effect ◽  
Coupling Constants ◽  
Radical Anions ◽  
Hyperfine Coupling Constants ◽  
Spin Resonance ◽  
Aliphatic Substituent

The hyperfine coupling constants for the radical anions of 2,3-dihydro- phenalene (perinaphthane) and 7,8,9,l0-tetrahydrocyclohepta[de]naphthalene have been determined from analysis of the electron spin resonance spectra in solution. The results are compared with data from other mono- and di-peri- substituted naphthalenes. A simple H�ckel molecular orbital treatment is used to describe the inductive effect of the aliphatic substituent.

Substituent effects on benzylic radical hydrogen hyperfine coupling constants. Part 4. The effect of branching of the alkyl substituent

1985 ◽  
Vol 63 (9) ◽  
pp. 2378-2383 ◽  
Author(s):  
Danial D. M. Wayner ◽  
Donald R. Arnold
Keyword(s):  
Hyperfine Coupling ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Esr Spectra ◽  
Coupling Constants ◽  
Molecular Orbital Calculations ◽  
Methyl Ethyl ◽  
Hyperfine Coupling Constants ◽  
Benzyl Radical ◽  
Spin Resonance

The effects of substituents in the meta and para positions of the benzyl radical on the α-hydrogen hyperfine coupling constants (hfc's) are discussed. The electron spin resonance (esr) spectra of the para-methyl, ethyl, isopropyl, and tert-butyl substituted benzyl and cumyl radicals are analysed. Hyperconjugation involving the C—C bond is 40–60% as effective as C—H hyperconjugation for delocalizing spin density. This conclusion is supported by INDO molecular orbital calculations. Similar analysis of the 13Cmr spectra of the para-alkyl substituted cumyl carbocations provides evidence that C—C hyperconjugation is 75–90% as effective as C—H hyperconjugation for delocalizing charge density.

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