The synthesis and properties of perthio-substituted benzene derivatives and of electron donor molecules with extended pi-conjugation - derived from benzenehexathiol - are described. The corresponding cation radical salts of the donor molecules are characterized as semiconducting solids. From 2,3,6,7-tetrachloro-naphthalene-1,4,5,8-tetrathiol oligomeric nickel and cobalt complexes with ferromagnetic spin ordering between 10 and 20 K are synthesized. The 4H,8H-thiopyrano[3,2-c]thiopyran-4,8-dione-3,7-dicarboxylic acid is obtained by cycloaddition reactions of 3H,6H-[1,2]-dithiolo[3,4-c]dithiole-3,6-dithione with dimethyl acetylenedicarboxylat. This new ligand for oxophilic metal ions gives polymeric complexes with transition metal ions. The crystal structure of the manganese complex was determined.