Reductions of thiazenes and some aspects of the chemistry of the RCN(_2)s(_2) ring system

Abstract

Reductions of the chlorothiazenes, S(_3)N(_2)C1(_2), S(_3)N(_2)C1 and S(_4)N(_3)C1 were studied using mainly i.r. spectroscopic and thin layer chromatographic techniques. The reactions gave solutions containing S(_4)N(_4), S(_4)N(_2), sulphur and (in the presence of moisture) traces of sulphur imides. A comparison was made between these new routes to, and the traditional preparation of, Inorganic applications for these S(_4)N(_4) solutions were investigated, and new routes are reported to S(_4)N(_4)-adducts and to S(_4)(NH)(_4) which avoid isolating solid (and potentially hazardous) S(_4)N(_4). Traces of (SN)(_x) were found in solutions produced by thiazene reductions where moisture was present. Vapour phase reactions of thiazenes with a hot catalytic surface were therefore investigated in attempts to find improved routes to (SN)^, especially with respect to industrial applications. A new iodinated derivative of (SN)(_x) was discovered, S(_3)N(_2)1(_x), in which the iodine content was strongly dependent upon the reaction conditions. Physical characterisation suggested that it was similar in nature to the recently reported brominated systems. In Part II of this work, as part of a general study of the 4-substituted -1,2,3,5-dithiadiazolium ring system, the reactions of aliphatic and aromatic nitriles and dinitriles with SC1(_2)/NH(_4)C1 were investigated. The new compounds CH(_3)CN(_2)S(_2)Cl,(CH(_3)CN(_2)S(_2))(_2) SnCl(_6) and C1-C(_6)H(_4).CN(_2)S(_2)Cl are reported and also a new route to the known compound, Bu^CN^S^Cl. By attempting the preparation of a series of compounds R.C(_6)H(_4).CN(_2)S(_2)C1 (where R was a para- substituted, electron-withdrawing group) some insight was gained into the mechanism of reaction of RCN with SC1(_2)/NH(_4)C1. Whilst investigating the reaction of adiponitrile with SC1(_2)/NH(_4)C1, a carbon-sulphur heterocycle, 3,4-dichloro-2,5-dicyanothiophene, was isolated. This represents the first product of a totally new synthetic route to 2,5-dicyanothiophenes.Chemistry of the dimeric dithiadiazole system was investigated, in particular, brief attempts were made to synthesise new C-S-N heterocycles by the desulphurisation of (PhCN(_2)S(_2))(_2).