Radicals Containing a 1,3-Dithiole Ring

Guimon, D. Gonbeau, G. Pfister-Guillouzo, K. Bechgaard, V. D. Parker, and C. T. Pedersen, Tetrahedron 29, 3695 (1973). 

Dithiolyl radicals are produced by photolysis of appropriate 1,2-di-thiolylium ions in ethanolic solutions.The reaction is a biphotonic process and involves ethanol as reductant. 

When the dithiole ring is annelated by phenalene, the laws of valence require the resultant aromatic heterocycle to be cationic reduction thus gives the neutral phenaleno[l,9-c(/][l,2]dithiolyl radical (138). This persistent radical has been examined in solution and its hyperfine splittings assigned on the basis of MO calculations. The radical is remarkably stable against dimerization it may be isolated as a paramagnetic solid whose mass 

Ethylation of l,2-dithiole-3-thione gives a 3-ethylthio-l,2-dithiolylium ion whose electroreductive dimerization has been investigated. A series of aryl-substituted l,2-dithiol-3-ylidene acetophenones underwent oxidative dimerization via cation-radicals (142) when electrolyzed the dimeric products, which contain a new C—C bond, were elaborated chemically into a series of highly conjugated derivatives including bithiathiophthenes.  

Astruc, M. Astruc, D. Gonbeau, and G. Pfister-Guillouzo, Collect. Czech. Chem. Commun. 39, 861 (1974). 

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