Dimethyl -tetraselenafulvalene

Kato R, Aonuma S, Okano Y, Sawa H, Tamura M, Kinoshita M, Oshima K, Kobayashi A, Bun K, Kobayashi H (1993) Metallic and supCTConducting salts based on an unsymmetrical Tt-donor dimethyl(ethylenedithio)tetraselenafulvalene (DMET-TSeF). Synth Met 61 199-206... 

Other organic superconductors are based on DMET (dimethyl-ethylene-dithio-diselenedithiafulvalene), an asymmetric molecule hybridized from ET and TMTSF [17]. According to its origin the physical properties are somewhere between one and two dimensional. Also based on asymmetric donors are the ambient-pressure superconductors (MDT-TTF)2Aul2 with Tc 3.5 K [18] and (DMET-TSeF)2A with X = A11I2 and I3 (7[ below 1K), where MDT-TTF stands for methylenedithio-TTF and DMET-TSeF for dimethyl-ethylenedithio-tetraselenafulvalene [19]. 

Dimethyl acetylenedicarboxylate reacts with carbon diselenide at 5000 atmospheres to yield the tetraselenafulvalene (229). The synthesis of symmetrically substituted tetrathiafulvalenes with long alkyl chains, e.g. compound (230 R = CnHas), by standard methods has been described. 

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