Calculation of the Hyperfine Coupling Constants of Some σ Electron Radicals

Abstract
The isotropic hyperfine coupling constants of cyclopropyl, vinyl, formaldiminoxy, formyl, and hydrogen cyanide anion radicals are calculated by a method which corresponds to the extension of the McLachlan procedure. These hyperfine coupling constants are then studied, and the contributions from the spin delocalization and spin polarization mechanisms are estimated. The role of one-center exchange integrals in the estimation of these hyperfine coupling constants is also studied; it is shown to be important in the claculation of the hyperfine coupling constants of the nuclei of the radical-center atom and of the atoms bonded to it.