Static and dynamic spin polarization
effects are distinguished. The static polarization
of an electron spin occurs in the
bonds of aromatic radicals where the σ-electron closest to an unpaired π-electron
tends to have its spin parallel to that of the π-electron. Likewise, static spin polarization
arises in the π-system of conjugated radicals: the electron of the doubly occupied
prefers to take a closer spatial position to the odd one, which spin is parallel
to the latter. The effect reflects the energy unfavourable situation if an electron
of opposite spin were to come nearby.
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook