Several bis(alkyldithio) derivatives of BDT-TTP (BTCn-TTP), where BDT-TTP is 2,5-bis(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene, have been synthesized. Cyclic voltammograms of new donors consist of four pairs of single-electron transfer waves, and the first redox potentials (E-1) are higher by 0.04-0.05 V than that of unsubstituted BDT-TTP. The TaF6- salt of bis(methylthio) derivative (BTM-TTP) have the so-called beta-type array of the donors. A tight-binding band calculation of (BTM-TTP)(2)TaF6 suggests that this salt. has a quasi one-dimensional Fermi surface. The BTM-TTP salts with the PF6- and TaF6- anions exhibit metallic temperature dependence down to 90 K, while the SbF6- salt is a semiconductor with the activation energy of 0.13 eV. (c) 2005 Elsevier B.V. All rights reserved.