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The radical anion derived from one-electron reduction of the diketone rá-10,11 -dimethylsuccindan-9,12-dione (1) behaves as a weakly interacting mixed valence compound. The unpaired electron apparently occupies an orbital derived from weak exchange interaction between the two aryl ketone subunits. This paper concerns interpretation of the unusual infrared absorption spectra of this species. These spectra do not include the characteristic absorptions of either structurally related monoketones or monoketyls. A simplified perturbational model is derived to describe vibrational states associated with C-0 stretching motions for weakly interacting ketone and ketyl. The frequency and oscillator strength of the relevant transitions are seen to reflect influences of the exchange interaction, V, and a parameter A£o which represents distortion of the potential energy surface by dissymmetric solvation and ion pairing interactions. The model is reasonably successful in quantitatively accounting for two of the more unusual bands in the spectra and values of V and A£q are consistent with other properties of the ion. Of particular interest is the conclusion that these transitions are truly vibronic, not simply vibrational, and that similar behavior should be anticipated for other mixed valence compounds.

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A new class of organic polymeric thin-film electrochromic materials is described. We show that the new polymer-modified electrodes change color reversibly in permanent thin-film form without the electrodeposition characteristics of organic liquid state systems such as the viologens. The polymer films exhibit good switching speeds (τ⩽100 ms), possess intrinsic memory, and show no chemical degradation or adhesion loss in preliminary life tests (104 cycles). It is demonstrated that several important electrochromic parameters can be varied by chemical modification of the polymeric material.

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