Bis(trimethylsilyl)sulfide

Bis(trimethylsilyl) sulfide is the chemical compound with the formula ((CH3)3Si)2S. Often abbreviated (tms)2S, this colourless, vile-smelling liquid is a useful aprotic source of “S2-“ in chemical synthesis.

Synthesis
The reagent is prepared by treating trimethylsilyl chloride with anhydrous sodium sulfide:
 * 2 (CH3)3SiCl +  Na2S  &rarr;  ((CH3)3Si)2S  +  2 NaCl

((CH3)3Si)2S must be protected from air because it hydrolyzes readily:
 * ((CH3)3Si)2S +  H2O  &rarr;  ((CH3)3Si)2O  +  H2S

Applications
(tms)2S is primarily used to convert oxides and chlorides into the corresponding sulfides. This transformation exploits the affinity of silicon(IV) for oxygen and halides. An idealized reaction is:
 * ((CH3)3Si)2S +  MO  &rarr;  ((CH3)3Si)2O  +  MS

In a similar way, it has been used in the conversion of aldehydes and ketones to the corresponding thiones.

Safety
((CH3)3Si)2S reacts exothermically with water, releasing toxic H2S.