NOVEL ONE-DIMENSIONAL ORGANIC CONDUCTOR BASED ON SELENIUM-CONTAINING BIS-FUSED TETRATHIAFULVALENE DERIVATIVE, (TSM-TTP)(I-3)(5 3)/

A novel selenium-containing bis-fused tetrathiafulvalene donor, TSM-TT P 1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene) forms a 3 : 5 tri iodide salt, (TSM-TTP)(I-3)(5/3). This salt has uniform one-dimensiona l columns of the donors, and is isostructural to the corresponding com plex of the sulfur analog. This compound shows a high electrical condu ctivity, 200 S cm(-1) at room temperature, and undergoes a metal-insul ator transition around 20 K. Another insulating (sigma(rt) = 0.03 S cm (-1)) phase with trimerized columns is also obtained.