Spin polarization, delocalization, and the effect of nonplanarity in hyperfine coupling constants of perfluorinated alkyl radicals.
Density functional calculations are presented on the structure and magnetic parameters of the perfluorinated ethyl and n-propyl radicals and compared with the non-fluorinated analogs. It is found that fluorine substitution leads not only to nonplanarity at the radical center but to delocalization of spin density onto the Falpha atoms and to spin polarization effects that both lead to pronounced anomalies in the anisotropic contribution to the hyperfine tensor. The nonplanar radicals do not obey the traditional McConnell relations. They serve as model systems for similar species that are observed in perfluorinated polymers.
Mitov
Svetlin
S
Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
Panchenko
Alexander
A
Roduner
Emil
E