Thiothionyl fluoride

Thiothionyl Fluoride and Difluorodisulfane. Thiothionyl fluoride [1686-09-9] S=SF2, and difluorodisulfane [13709-35-8] FSSF, are isomeric compounds which may be prepared as a mixture by the action of various metal fluorides on sulfur vapor or S2CI2 vapor. Chemically, the two isomers are very similar and extremely reactive. However, in the absence of catalytic agents and other reactive species, FSSF is stable for days at ordinary temperatures and S=SF2 may be heated to 250°C without significant decomposition (127). Physical properties of the two isomers are given in Table 6. The microwave spectmm of S=SF2 has been reported (130). 

In addition to these well-known fluorides, there are others that include a form of S2F2 that is actually thiothionyl fluoride, SSF2, SF2, and S2F10, in which two SF5 groups are linked by an S-S bond. 

Thiothionyl fluoride, 8=8F2 (an isomer of 82F2), is also known, although it is not especially stable it is often obtained mixed with disulfur difluoride, but may be obtained directly by reaction of NF3 with sulfur or by the fluorination of 82CI2 with KF in 8O2. 

Nitrogen trifluoride passed into molten sulfur at 350 to 400°C reacts to give thiothionyl fluoride, SSF2, and thiazyl fluoride, NSF, as main products and smaller amounts of SF4, SFe, and SO2F2. The composition of the product mixture depends on the depth of the molten sulfur layer and the contact time of the NF3. Below 350°C, small amounts of N3S3F3 are formed [1]. The combustion of sulfur with nitrogen fluoride in a nickel bomb proceeds according to the... 

The lower fluorides, S2F2 and SF4, disproportionate readily into sulfur and SF6. The difluoro compound, S2F2, demonstrates unusual structural isomerism in that it can exist in two forms disulfur difluoride, F—S—S—F (12.8) and thiothionyl fluoride, S=SP2 (12.9). 

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