ABSTRACT

Organic ion-radicals carry a charge and an unpaired electron. Their distribution along a molecular contour determines ion-radical reactivity. Therefore, it is important to elucidate the principles that control organic ion-radical reactivity. As already noted, the main energetic characteristics of ion-radicals are connected with the MOs occupied by one (unpaired) electron. These orbitals are also named SOMOs. For the ion-radicals formed from nonpolar or not so strong polar molecules, SOMO encompasses atoms of the molecular carcass with an unpaired electron and the charge is equally distributed. For the ion-radicals formed from molecules with a signi cant charge separation, an unpaired electron is still located on the SOMO, but the charge is not equally distributed within the carcass. In the latter case, other occupied MOs can respond to make the so-called uncoupled situation. In an extreme case, spin and charge can sometimes be completely scattered forming distonic ion-radicals. These ion-radicals are considered in Section 3.2.4.