Cyanogen Sulphide, (CN)₂S

This compound results from the interaction of silver thiocyanate and cyanogen iodide. It is formed in ethereal solution, consequent on the separation of the very insoluble silver iodide:

CNSAg + CNI = AgI + (CN)₂S.

The sulphide crystallises from carbon disulphide solution at 0° C. in rhombic tablets, which sublime above 30° C. and melt at 60° C., and dissolve in water, alcohol, and ether, but are decomposed by alkalis, like other thioanhydrides, into a mixture of thio- and oxy-salt:

(CN)₂S + 2KOH = CNSK + CNOK + H₂O.

Cyanogen selenide, (CN)₂Se, also exists.