Optical properties of the conducting salt (DOEO)4HgBr4 . TCE

A new charge transfer (DOEO)4HgBr4 . TCE salt based on [(1,4-dioxane-diyl-2,3-ditio)ethylenedioxytetrathiafulvalene] (DOEO) and [HgBr4]2- anion was synthesized and characterized by spectral analysis. The structure consists of alternating organic and inorganic layers. The inorganic layers are formed by [HgBr4]2- anions and 1,1,2-trichloroethan (TCE) solvent molecules. The organic layers are built of dimerized DOEO stacks. Polarized reflectance (from 500 to 18,000 cm-1) and Raman spectra of single crystals were studied down to the liquid helium temperature. An electronic dispersion in IR spectra was analyzed in terms of the Lorentz model and optical transport parameters were determined. The proposed assignment of vibrational features of (DOEO)4HgBr4 . TCE salt was based on ab initio calculations of the normal modes of DOEO0, DOEO+, and TCE molecules. The analysis of the spectra in terms of the isolated dimer model yields reliable estimates of DOEO electron-molecular vibration (e-mv) coupling constants