The parent compound, the 1,2-dithiolylium ion, can by successive addition of vinylenethio groups give rise to higher polycyclic systems each composed of 1,2-dithiole rings with the sulfur atoms in a row. Until now, however, it has only been possible to extend the system to compounds with 3 (l,6,6aλ4-tri-thiapentalene), 4 and 5 sulfur atoms in a row. The discussion of the structure of these systems has been based on results obtained by use of X-ray crystallography, electron diffraction,1H NMR-, 13CNMR-, ESR-, Infrared-, microwave-, ESCA-, photo-electron spectroscopy and mass spectrometry. The results from other physico-chemical studies such as photo- and electrochemical studies have also been used in the discussion of bonding and structure. Physico-chemical data from the period 1970-1979 are included.