Dithiolium salt explained

Dithiolium salts are compounds of the formula [(RC)<sub>3</sub>S<sub>2</sub>]+X (R = H, alkyl, aryl, etc.). These salts consist of a planar organic cation with a variety of anions such as halides. The five-membered ring cations are observed in either of two isomers, 1,2- and 1,3-dithiolium cations. These cations differ with respect to the relative positions of the pair of sulfur atoms. Both isomers feature a planar ring, which is aromatic owing to the presence of 6π electrons.[1] For example, the 1,2-ditholium ring can be represented as an allyl cation of the three carbons, with each sulfur atom donating one of its lone pairs of electrons to give a total of three pairs.

Preparation, occurrence, reactions

1,2-Dithiolium cations have been prepared from 1,3-diketones by treatment with H2S and oxidants such as bromine.[2]

1,3-Dithiolium cations are often prepared by alkylation of the corresponding unsaturated dithio- or trithiocarbonates:

The analogous reaction of electrophiles with 1,2-dithiole-2-ones affords 1,2-dithiolium cations.

References

  1. Book: 27 . 1981. 151–239. Advances in Heterocyclic Chemistry. The 1,2- and 1,3-Dithiolium Ions. Noël Lozac'h . Madeleine Stavaux . 10.1016/S0065-2725(08)60997-6. 978-0-12-020627-8 .
  2. 10.1021/jo00954a028. Improved Synthesis of Alkyl Substituted 1,2-Dithiolium Salts. Hendrickson, A. R. . Martin, R. L. . Journal of Organic Chemistry. 1973. 38. 14 . 2548–9.