Recent Development of Organic Conductors Containing Selenium Atoms: New Synthetic Methods, Electron Donors, and Conductors

The recent development of selenium-containing tetrathiafulvalene (TTF)-type electron donors is described, in terms of the synthetic chemistry and thus developed new electron donors and (super)conductors. Introduction of two breakthrough reactions, the one-pot preparation of 1, 3-dichalcogenole-2- chalcogenones from terminal alkynes and the formation of heterocyclic rings via transalkylation on a chalcogen atom, has made it possible, in combination with conventional trialkyl phosphite-promoted coupling reaction, to synthesize various selenium-containing TTF-type electron donors. In particular, the synthetic method is very useful for the synthesis of various tetraselenafulvalene (TSF) derivatives so far inaccessible. Such new electron donors include methylenedithiotetraselenafulvalene (MDT-TSF) and methylenedithiodiselenadithiafulvalene (MDT-ST), both of which produce a series of unique organic superconductors with T_c = 3.2-5.5 K.