Dithiadiazolium cations

The first examples of the 1,2,3,5-dithiadiazolium cation (11.1) were obtained from the treatment of organic nitriles with This... 

The 1,2,3,5-dithiadiazolium cation (78) is obtained by the reaction of organic nitriles with (NSC1)3, which proceeds by the intermediate formation of six-membered ring systems of the type RCN3S2C12 (Equation 2).210... 

The first examples of the 1,2,3,5-dithiadiazolium cation (38) were obtained in 1977 from the treatment of organic nitriles with (NSC1)3. This reaction has subsequently been shown to proceed by the intermediate formation of S,S -dichlorodithiatriazines (39). Another route to (38) involves the cyclocondensation of trisilylated amidines with sulfur dichloride (equation 20). This method is readily extended to the synthesis of multidithiadiazolium cations, for example, 1,3,5-C6H3(CNSSN)32+.i 3... 

The results from mass spectrometric analysis of the bicyclic systems 23 depend on the ionization method applied. With El, molecular ions are mostly detected, but with low intensity. The peak representing the fragment [M-N3S] is always present. This corresponds to the stable 1,2,3,5-dithiadiazolium cation b. The more gentle El method allows for the detection of molecular ions and the direct degradation products and are observed, together with the ions (c, d ) formed by recombination of the fragments <2003EJI3211>. 

In a separate example, the 4-phenyl-l,2,3,5-dithiadiazolium cation in the presence of [S3N3] gave 4-phenyl-1,2,3,5-dithiadiazolylium-l,3,5,2,4,6-trithiatriazinide 16. Ab initio calculations show that the ionic charges of the two rings are... 

The isomeric 1,3,2,4-dithiadiazolium cation (40) is prepared by the (4 + 2)7t cycloaddition of the NS2+ cation to the C N triple bond of organic nitriles (see Figure 2). The NS2+ cation also reacts with polycyano compounds, for example, dicyano- and tricyanobenzenes, to give the corresponding bisand tris(dithiadiazolium) cations. 

In this chapter the dithiadiazole family is reported for the very first time. Since these fascinating five-membered heterocyclic cations, radicals, and dimers were not covered in CHEC-I(1984) and CHEC-II(1996), the discussion encompasses all available literature rather than focusing solely on publications post-1995. Before any further discussion, an appreciation of the two isomeric forms and the nomenclature associated with each is essential. The 671 cyclic systems of 1,2,3,5-dithiadiazolium chloride 1 and 1,3,2,4-dithiadiazolium chloride 2 are shown below. As this chapter demonstrates, the 1,2,3,5-isomeric form dominates the literature in this field, reflecting the wider synthetic opportunity and stability associated with it. 

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