Macrocycles tetrasulfides

Gentle oxidation of thiols generally leads to disulfides. When tetrafluorobenzene-1,4-dithiol is added to dimethyl sulfoxide, it quickly dissolves with warm evolution and a color change of the solution, from which a macrocyclic tetrasulfide 1 precipitates in 95% yield.285... 

Although the polysulfur macrocycles became more interesting to the scientific community after Pedersen s report of the crown compounds (see Chap. 1), examples of such structures may be found in the literature dating back some time. The first report of a macrocyclic polysulfide appears to be that by Ray who found in 1920 that when 1,2-dimercaptoethane and 1,2-dibromoethane were heated with alcoholic potassium hydrogen sulfide as shown in Eq. (6.2), triethylene trisulfide (2) and a substance presumed to be triethylene tetrasulfide (3) could be isolated. 

Many exotic electrophiles have been shown to react with co-ordinated thiolate for example new disulfide bonds may be formed by reaction with S2C12. The nickel(n) complex of a very unusual tetrasulfide macrocyclic ligand may be prepared by this method (Fig. 5-83). Notice that this reaction utilises the nickel complex of the N2S2 ligand prepared by a metal-directed reaction in Fig. 5-78. 

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