Synthesis and X-ray crystal structure of a selenophenoquinonoid-extended donor, BEDT-BDTS, affording highly conducting tetracyanoquinodimethane and I-3 complexes

2,5-Bis(4,5-ethylenedithio-1,3-dithiol-2-ylidene (BEDT-BDTS), a selenophenoquinonoid-extended analogue of bis(ethylenedithio) tetrathiafulvalenes (BEDT-TTF), has been synthesized as a promising candidate for an electron-donating component of high T-c organic superconductors. BEDT-BDTS is air-stable and has a significantly enhanced electron-donating ability compared with that of BEDT-TTF. The molecular and crystal structures of BEDT-BDTS have been determined by single crystal X-ray analysis in which short intermolecular S ... S contacts have been found in the side-by-side directions of the donor arrangements. A 1 : 1 TCNQ complex and a 3 : 1 I-3(-) radical cation salt of BEDT-BDTS have been obtained and proved to exhibit fairly high room temperature conductivities.