A new semiconducting ternary compound of stoichiometry TEDA•I2.5•TCNQ is reported. The crystal is made up of linear chains of TCNQ−1/2, nonlinear chains of I3−, and monodides of doubly charged triethylenediamines (TEDA). Half the TEDA's are hydrogen bonded to the TCNQ's and I3−. The conductivity measurements indicate semiconducting behaviour with two discontinuities in activation energy, one at high (330 K) and the other at low (160 K) temperatures. Resonance Raman spectra of the crystals manifest strong resonance enhancement of the iodide moieties. In particular, selective resonance excitation at 647 nm of nonsymmetric I3− is observed, thus indicating an increasing asymmetry of the I3− in the low temperature phase and suggesting coupling between the three species in this phase.
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Bandrauk et al. (1989) studied this question.