Spin Density Distribution and Energy Stabilization in the Cation Radicals of Multilayered Compounds

The spin density distributions and the energy stabilizations in the polymer cation radicals (Rn+·) have been investigated by measuring the oxidation potentials (E1⁄2°) and the electron spin resonance (ESR) spectra of the cation radicals generated by the electrochemical oxidations of some multilayered compounds. E1⁄2° decreased monotonically as the number of layers increased. The spin densities on the aromatic rings have been estimated from the hyperfine coupling constants with the help of the McLachlan’s and INDO calculation. It was found that the spin density tends to localize in the central moieties in Rnn+·. The localization of the spin density and the energy stabilization are interpreted with a simple theoretical model of Rnn+·, which takes into accounts the repulsion integral (γ1) and resonance integral (ζ) between the nearest neighbor molecules. The comparison with the experimental data has lead to the numerical estimates of γ1=0.1 eV and ζ=0.4 eV.