Triimide

The formal replacement of a sulfur atom in cyclo-S generates S7NH (6.1), the first member of a series of cyclic sulfur imides that includes the three diimides 1,3-, 1,4-, and 1,5-S6(NH)2 (6.2-6.4), two triimides 1,3,5-and 1,3,6-S5(NH)3, and S4N4H4 (6.5). Isomers of these ring systems containing adjacent NH groups are not known. 

The tetraimidosulfate anion [S(NtBu)4] , isoelectronic with 804 , is prepared by a methodology similar to that employed for the synthesis of triimidosulfites. The reaction of the sulfur triimide S(N Bu)3 with two equivalents of LiNH Bu produces the solvated monomeric complex [(thf)4Li2S(N Bu)4] (10.21) (Eq. 10.8). The nucleophilic addition of... 

In the case of the sulphur triimide S(NBu-f)3, the dispersive Raman technique applying a double monochromator and a CCD camera was employed to obtain the information from polarized measurements (solution studies) and also to obtain high-resolution spectra by low-temperature measurements. In the case of the main group metal complex, only FT-Raman studies with long-wavenumber excitation were successful, since visible-light excitation caused strong fluorescence. The FT-Raman spectra of the tetraimidosulphate residue were similar to those obtained from excitation with visible laser lines. 

In conclusion, the Raman spectroscopic experiments and the assignment of the SN vibrations to much lower wavenumbers than previously reported suggest a mainly electrostatic contribution in the > S —N —bond of sulphur triimides and related metal complexes. The hypothesis of valence expansion at sulphur to three covalent double bonds [S(=NR3)] seems no longer valid . 

The triimide is stable at atm. temp. it decomposes above 400°, chiefly with the rupture of the silicon bridge, and the formation of some silicocyanogen, Si2N2. These compounds are very sensitive to oxygen, and particularly to moisture. A. Stock and F. Zeidler obtained silicon dihydrotriimide ... 

According to E. Scandola, when hydrazine is added drop by drop to finely granulated sodium suspended in ether, and then heated on a water-bath with a reflux condenser, a white substance is formed which explodes in air. If left in contact with the ether, it loses its explosive property. The white compound does not act on silver nitrate in ammoniacal soln. Its structure is supposed to correspond with sodium triimide or sodium hydrazide ... 

E. Raschig thought that in the reaction between sodium hydroxide and chloramine (q.v.), it is probable that there is formed some triimide, N3H3, or... 

For sodium triimide, vide the action of sodium on hydrazine. The inclination of nitrogen to form long chains and closed rings is far less than is the case with carbon with the latter, there seems an almost unlimited number of hydrogen compounds with nitrogen, comparatively few are known, and these are usually unstable bodies, often explosive. 

Phosphorus Triamide, P(NH2)3, is said to be formed by the action of dry ammonia on phosphorus tribromide at -70° C. It was a yellow solid which decomposed at 0° C. giving a brown substance, diphosphorus triimide, P2(NH)3, and was further decomposed on further heating into phosphorus, nitrogen and ammonia.2... 

A different type of trimerization is exemplified by 1,4-dithiintetra-carboxylic acid diimide which, on heating at 120° in pyridine, gave a mellitic acid triimide (181 R = H, Me, CH2Ph) probably through the highly strained intermediate260 [Eq. (11)]. 

There is an extensive chemistry of heptasulfur imide, from which many inorganic and organic derivatives have been made. The chemistry of the diimides and triimides is only just beginning to be studied, and promises to be even more interesting. 

The 1,3,6- and 1,3,6-pentasulfur triimides come off the column after the diimides, but they cannot easily be isolated by merely continuing elution in the procedure just described, because inordinately large volumes of solvent would be needed, t... 

For the triimides, it is expedient to increase the scale of the preparation, and then to effect a preliminary concentration of the triimides from the other imides so that the chromatography can be done on a much smaller column. The crude imide mixture is made as just described, but uang 3 1. of dimethylfonn-amide and 420 ml. (5.2 moles) of disulfur dichloride. After grinding finely once or twice as before, it is extracted with successive portions of dry, peroxide-free ethyl ether, totaling 3 1. The combined ether extracts are left to evaporate spontaneously until 150-300 ml. of cold liquid is left. Evaporation is continued until it is judged that more than half of the solute has crystallized. The solution is decanted away from the mass of crystals of heptasulfur imide and hexasulfur diimides, and allowed to evaporate to dryness, leaving 30-40 g. of solid, which consists... 

The cyclic sulfur imides are odorless, nearly colorless solids. All are well crystallized the 1,3,5-triimide appears as fine needles, w hereas all the others are orthorhombic crystals... 

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