CYCLOADDITION REACTIONS OF SNSASF6 WITH ARYL NITRILES AND DIPHENYLACETYLENE - THE PREPARATION AND CHARACTERIZATION OF ARYL 1,3,2,4-DITHIADIAZOLE AND 1,2,3,5-DITHIADIAZOLE RADICALS

The SNS+ cation (in SNSAsF6) underwent symmetry-allowed concerted cycloadditions with the aryl nitriles RCN (R = 2,5-Me2C6H3, Ph, p-O2NC6H4, and 3,5-(O2N)2C6H3) and diphenylacetylene. The cycloadducts RCNSNSAsF6 (R = 2,5-Me2C6H3, Ph, p-O2NC6H4, and 3,5-(O2N)2C6H3) and Ph CSNSCPhAsF6 were characterized by elemental analyses and IR and NMR (H-1, C-13, N-14) spectroscopies. The reduction of RCNSNS+ gave the corresponding 1,3,2,4-dithiadiazoles RCNSNS., which in turn rearranged to the corresponding 1,2,3,5-dithiadiazoles RCNSSN.. The rate of this rearrangement was correlated with the ionization potentials of the corresponding nitriles. The radicals RCNSNS. (R = Ph, p-O2NC6H4) were isolated as pure compounds, and characterized by mass spectrometry, IR, FT-Raman, and ESR spectroscopies. The reduction of PhCSNSCPh+ led to neutral radical PhCSNSCPh., which is stable in solution up to ca. 0.5 M, but decomposes at higher concentrations.