Ferromagnetic spin-coupling 4,4"-through metaterphenyl:: models for high-spin polymers

Model diradical dications have been synthesised which have the 4,4"-through metaterphenyl spin-coupling pathway found in arylamine high-spin polymers. In the model triplet diradical dication derived by a two-electron oxidation of N, N, N", N"-tetrakis(4-tert-butyl-2-methoxyphenyl)3,3"- dimethoxy[1,1'; 3',1"] terphenyl-4,4"-diamine the separation between the triplet and singlet states was found to be 0.083 kcal mol(-1). This value is close to that predicted on the basis that the energy difference should be proportional to the product of the spin densities in the 'common' ring ( the ring in which the two spin densities overlap). This is an important principle in the design of new high-spin polymers.