Structure and spectral studies of the BEDO-TTF radical cation salt with isocyanuric acid anion

A new radical cation salt based on bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF) and the isocyanuric acid anion (C3H2N3O3)(-) was synthesized and characterized by X-ray and spectral analysis. The unit cell of (BEDO-TTF)(2)(C3H2N3O3) is triclinic, space group P (1) over bar, a = 3.974(1) angstrom, b = 5.429(2) angstrom, c = 18.720(7) angstrom, alpha = 86.26(3)degrees, beta = 84.65(3)degrees, gamma = 81.13(3)degrees. The crystal structure is layered one and the donor packing is beta-type. IR and Raman spectra of single crystals and UV-Vis-NIR absorption spectra of the sample dispersed in KBr pellet were analyzed. The normal mode vibrations and the intramolecular excitations of the neutral BEDO-TTF molecule, BEDO-TTF+ cation and (C3H2N3O3)(-) anion were calculated using the density functional theory. On the base of these calculations an assignment of the vibrational and electronic features in the experimental spectra was proposed. Moreover, analyzing the normal modes related to the C=C vibrations it was found that the average charge on the donor molecule is equal +0.5 e. (c) 2006 Elsevier B.V. All rights reserved.