Dithiins and 1,4-Diselenins

4-Dithiin (38) and its 2,3-dihydro-derivative (39) undergo S-ethylation with triethyloxonium fluoroborate giving the sulphonium salts (40) and 

Bandoli, D. A. Clemente, C. Panattoni, A. Dondoni, and A. Mangini, Chem. Comm., 1970, 1143. 

Empirical resonance-integral parameters have been derived for C—S TT-bonds in tetracyano-l,4-dithiin (47) and thianthrene. Dithiin (47) undergoes ready aminolysis with secondary amines giving salts (48) which. 

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