The synthesis and electrochemical properties of di- and tetra-halogenated t
etraselenafulvalene (TSF) derivatives are presented. The synthetic method i
nvolves an efficient formation of halogen substituted 1,3-diselenole-2-selo
nes from readily available starting materials. Electrochemical crystallizat
ion afforded several radical cation salts, and, of them, the ClO4 salt of t
he dimethyl-dibromo-TSF showed a high conductivity of 400 S cm(-1) at room
temperature and retained metallic down to ca. 90 K.