Sulfur dicyanide is an inorganic compound with the formula S(CN)2. A white, slightly unstable solid, the compound is mainly of theoretical and fundamental interest given its simplicity.[2]: 8 It is the first member of the dicyanosulfanes Sx(CN)2, which includes thiocyanogen ((SCN)2) and higher polysulfanes up to S4(CN)2.[3] According to X-ray crystallography, the molecule is planar, the SCN units are linear, with an S-C-S angle of 95.6°.[4]
Sulfur dicyanide begins to sublime at 30-40 °C and melts at 60 °C.[5] Under an inert atmosphere, it slowly decomposes to a yellow polymer at room temperature with a rate increasing in temperature.[2]: 8, 14 The compound is unstable in acid, disproportionating to thiocyanate, cyanate, hydrogen sulfate,and cyanide,[1] and neutral moisture induces decomposition to thiocyanic and cyanic acids. Stable solutions are possible in many organic solvents.[2]: 14
Sulfur dicyanide generally reacts with noble metals to give heteroleptic cyano-thiocyano complices, although in rare cases it can ligate without decomposition, e.g.:[2]: x
^ abWilson, I. R.; Harris, G. M. (January 1, 1961). "The oxidation of thiocyanate ion by hydrogen peroxide II: The acid-catalyzed reaction". Journal of the American Chemical Society. 83 (2). doi:10.1021/ja01463a007.