NONCLASSICAL CONDUCTING POLYMERS - NEW APPROACHES TO ORGANIC METALS

J.A. Berson recently described new meta phenylene bridged dimethylenet hiophenes, -pyrroles, and -furans and suggested them as building block s for conducting materials. The structural principles determining the presence or absence of magnetic ordering in such linear conjugated pol ymers with narrow, partially filled bands are discussed here on the ba sis of topological criteria and former work in solid-state theory, wit h major concern about the practicability of the suggested models. It s eems that the suggested molecules rather are models in which the natur e of spin-spin interaction in and between the subunits is controlled, but that conducting properties will still be difficult to achieve.