Thiazyl trifluoride is a chemical compound of nitrogen, sulfur, and fluorine, having the formula NSF3. It exists as a stable, colourless gas, and is an important precursor to other sulfur-nitrogen-fluorine compounds. It has tetrahedral molecular geometry around the sulfur atom, and is regarded to be a prime example of a compound that has a sulfur-nitrogen triple bond.

Preparation

NSF3 can be synthesised by the fluorination of thiazyl fluoride, NSF, with silver(II) fluoride, AgF2: or by the oxidative decomposition of FC(O)NSF2 by silver(II) fluoride: It is also a product of the oxidation of ammonia by S2F10. Direct fluorination of mercury difluorosulfinimide (Hg(NSF2)2) does not give thiazyl trifluoride, but instead the isomeric fluoriminosulfur difluoride (F2SNF).

Reactions

NSF3 is much more stable than thiazyl fluoride, does not react with ammonia and hydrogen chloride, and only reacts with sodium at 400 °C. However, the fluoride ligands are labile, and can be displaced by secondary amines. Thiazyl trifluoride reacts with carbonyl fluoride (COF2) in the presence of hydrogen fluoride to form pentafluorosulfanyl isocyanate (SF5NCO).