Ethenedithione

Ethenedithione or ethylenedithone is an unstable chemical substance with formula S=C=C=S made from carbon and sulfur.
Ethenedithione can exist as a gas at low pressure and high temperature, but is unstable when condensed or under higher pressure.
It can be stabilized as a ligand binding two cobalt atoms.
Other occurrences as a ligand are in TpW₂^– and ₂Ni₂, where Tp is trispyrazolylborate.

Formation

Ethenedithione can be made by the flash vacuum pyrolysis of 2,5-Dithiacyclopentylideneketene.
Also it has been made by dissociative ionization of tetrathiapentalenedione, and then neutralisation of ions produced.
C₂S₂ is made along with carbon subsulfide and carbon monosulfide, in an electric discharge in carbon disulfide vapour.

In its ground state it is a triplet state. Ethenedithione can be trapped in a matrix of solid argon without decomposition.
The infrared spectrum contains a prominent line at 1179.3 cm⁻¹ due to asymmetric C=S stretch of the most common isotopes.
Over 60 K, ethenedithione polymerises. Possible polymerisation products include polythiene.