Organic polymers with indirect magnetic interaction caused by the symmetry of the elementary units

Abstract

The magnetic properties of a class of 1-D π-systems having a frontier half-filled band of degenerate MOs localized within the elementary units (EU) were studied theoretically. The localization of the MOs is caused by the symmetry of the π-fragments which form the EUs. The localization and non-overlapping of the MOs results in vanishing of the direct (Hund) and the kinetic exchange interaction between the unpaired electrons. The indirect exchange of the unpaired electrons (spin-polarization exchange) occurs via the delocalized π-electrons in the filled energy bands. An approach allowing the calculation of the indirect exchange interaction is applied for a class of polymers having pyrene, azulene, and s-indacene as fragments of the EUs. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 66: 425–434, 1998