Tetrathiatetraza-azulene

Abstract

Tetrasulfur tetranitride 1 reacts with phenyl vinyl sulfoxide 3 or sulfone or phenyl vinylsulfonate to give the planar delocalised 14 Π electron aromatic system 1λ4δ2, 3,5, 7λ4δ2-tetrathia-2,4,6,8-tetraza-azulene 4 as stable dark metallic lustrous crystals. All the sulfur and nitrogen atoms of S4N4 have been retained and a C-C Π bond incorporated, the 12 Π cage structure of S4N4 being converted into the planar bicyclic system. A mechanism is proposed for this transformation. The ability of the vinyl component to act as an acetylene equivalent and to suffer dehydrogenation to give the aromatic product appear to be necessary for this type of reaction since more highly substituted sulfoxides lead only to decomposition. Optimum conditions for the reaction of phenyl vinyl sulfoxide with S4N4 (3.6 equiv.) in refluxing xylene for 7.5 h give the tetrathiatetraza-azulene 4 in 35%.