Heptathiazocine and Tetrabutylammonium Tetrathionitrate

Submitted by J. BOJES, T. CHIVERS, and I. DRUMMOND Checked by RALE STEUDEL+ and FRITZ ROSE+ 

The well-established synthesis of cyclic sulfur imides from disulfur dichloride and ammonia in A,A -dimethylformamide requires close attention and gives rise to S7NH, Se(NH)2 isomers, and Ss(NH)3 isomers in approximate yields of 

4% (based on S), respectively. A more convenient procedure for the preparation of S7NH alone in yields up to 41% (after chromatographic separation) is the reaction of sodium azide with elemental sulfur in hexamethyl-phosphoric triamide. The deep-blue intermediate, which is dramatically apparent in the synthesis of cyclic sulfur imides, has been identified as the [NS4] ion. This ion is isolated as its tetrabutylammonium salt from the reaction of S7NH with [(C4H9)4N] OH in diethyl ether at low temperature. 

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