It is most likely S2Cl2, with an existing double bond between the two sulfur atoms. The structural formula would look like this:
Disulfur dichloride is a covalent compound, sharing electrons between the atoms of sulfur and chlorine. It is a yellowish-green color that smokes in the presence of water. The angles between the two sulfur-chlorine bonded parts are at 90 degrees with respect to each other. The reaction is easily reversible and delivers up hydrochloric acid when added to water. The creation of sulfur mustard gas is also possible when combining disulfur dichloride with ethylene gas. Sulfur is a yellow element which has a characteristic rotten egg smell. Chlorine is a greenish colored gas and a member of the halogen family on the periodic table of elements.