Hybrid Molecular Materials Based upon Organic π-Electron Donors and Inorganic Metal Complexes. Conducting Salts of Bis(ethylenediseleno)tetrathiafulvalene (BEST) with the Octahedral Anions Hexacyanoferrate(III) and Nitroprusside

The synthesis, structure and physical characterization of three new radical salts formed by the organic donor bis(ethylenediseleno)tetrathiafulvalene (BEDS-TTF or BEST) and the paramagnetic hexacyanoferrate(III) anion [Fe(CN) 6] 3− or the photochromic nitroprusside anion [Fe(CN) 5NO] 2− are reported: (BEST) 4[Fe(CN) 6] ( 1), (BEST) 3[Fe(CN) 6] 2·H 2O ( 2) and (BEST) 2[Fe(CN) 5NO] ( 3). Salts 1 and 3 show a layered structure with alternating organic ( β –type packing) and inorganic slabs. Salt 2 shows an original interpenetrated structure probably due to the unprecedented presence of (BEST) 2+ dications. The three salts are semiconductors although salt 1 exhibits a high room temperature conductivity and a semiconducting–semiconducting transition at ca. 150 K which has been attributed to a dimerization in the organic sublattice.