Binary Cyclic Nitrogen-Sulfur Anions

Submitted by J. BOJES, T. CHIVERS, and R. T. OAKLEYt Checked by G. WOMERSHAUSER and M. SCHNAUBERt 

Tetranitrogen tetrasulfide is prepared by the method of Villena-Blanco and Jolly. Piperidine is stored over 4-A molecular sieves and pentane over calcium hydride. Absolute ethanol is heated at reflux with magnesium turnings and a few crystals of iodine for 4 hr. The solvents and piperidine are distilled immediately before use. The reaction is conducted under an atmosphere of dry nitrogen in a one-necked flask (200 mL) equipped with a side arm. 

The compounds [PPN] [N5S4] and (Pli4As] (N5S4] are yellow, crystalline solids soluble in dichloromethane and warm acetonitrile or ethanol. Solid [PPN] [N5S4] can be stored for years in a glass vial without special precautions. Solutions should be handed in an inert atmosphere to prevent oxidation or hydrolysis. 

Salts of the N3S3 ion are yellow or greenish-yellow solids, soluble in di-chloromethane or acetonitrile and slowly oxidized on exposure to air. The PPN salt is less susceptible to atmospheric oxidation than salts containing R4N+ or alkali metal cations. In solution, oxidation of N3S3 occurs more rapidly. It is easily detected by a change in color from yellow to red due to the formation of N3S30 509 nm). Solid samples should be stored 

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Sulfur and nitrogen form a variety of binary anions with acyclic, cyclic and cage structures.69,70 The Se-N anions are only known in metal complexes. S-N anions play an important role in the formation of cyclic sulfur imides and as constituents of solutions of sulfur in liquid ammonia. 

Sulfur and nitrogen represent a versatile combination in the formulation of binary anions with cyclic, cage, or catenated structures, none of which have counterparts among the known N-0 anions. In addition, several S-N anions are known only in complexes with transition metals (see Section 8.5). 

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