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 seleno phenoquinonoid-extended analogue of bis(ethylenedithio) tetrathiafulva lenes (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 str uctures of BEDT-BDTS have been determined by single crystal X-ray anal ysis in which short intermolecular S ... S contacts have been found in the side-by-side directions of the donor arrangements. A 1 : 1 TCNQ c omplex and a 3 : 1 I-3(-) radical cation salt of BEDT-BDTS have been o btained and proved to exhibit fairly high room temperature conductivit ies.