1,2,4-Thiadiazoles

Investigations on Organo–Sulfur–Nitrogen Rings and the Thiocyanogen Polymer, (SCN)x

“…Although some of these 1,2,4-thiadiazoles have been synthesised before, the spectroscopic data is very limited [19,[24][25][26] and only one compound has published 13 C NMR data. [27] We also report the synthesis of model compounds composed of two 1,2,4-thiadiazole rings linked by a sulfur bridge.…”

5‐Chloro‐3‐methylthio‐1,2,4‐thiadiazol‐2‐ium chlorides as useful synthetic precursors to a variety of 6aλ4‐thiapentalene systems

“…To the best of our knowledge, systems of this type have been limited to 5-aryl-and 5-(dialkylamino)-1,2,4-thiadiazolium salts through the oxidative ring closure of N-thionoamidino compounds in the presence of perchloric acid [4].…”

“…We suggest a course via an unstable carbamic acid (Scheme 3). The 2-methyl-3,5-diphenyl-1,2,4-thiadiazolium salts were shown to be similarly cleaved by H 2 O with elimination of sulfur [4]. The source of instability of 3d,e lies rather in the nature of the Nsubstituent as these salts spontaneously decomposed in solution into a mixture of tert-butyl chloride, isobutene, and 5-chloro-1,2,4-thiadiazoles 6.…”

“…We have previously reported [1] the reaction of sulfenyl thiocyanates with a series of (methylthio)-and (arylthio)formimidoyl isothiocyanates 1 readily forming the compounds 2, which may be designated as 6H-1,6a 4 -dithia-3,4,6-triazapentalenes. This result was explained by a nucleophilic addition to the C S unsaturation of the heterocumulene 1, with subsequent cyclization and displacement of the sulfenyl anion (Scheme 1).…”

“…Study of such isolable aromatic species has attracted much attention over the past decades because of their unique binding behavior [3][4][5]. It has been pointed out that their structure may be the result of the existence of a "single-bond-no-bond" SCHEME 1 resonance between several canonical forms, represented by the three general formulas in Scheme 2.…”