Nitrogen triazide

FIGURE 6 Structures of some quantum chemically investigated, still hypothetical, homopolyatomic nitrogen species. Proceeding from top left to bottom right pentazole anion (Dgh), azidopentazole (Cs), octaazapentalene (D h), bispentazole ( d)< hexaaza De-war benzene (C2v) hexaazabenzvalene (C ), hexaazaprismane ( h). twisted boat (D ), diazide (C2), nitrogen triazide (C3). 

For the elusive nitrogen triazide species Nio (also see Fig. 6), the cis structure (C3) was calculated to be the most energetically favorable form but significantly less stable than the D2d symmetric bispentazole (see above). We close this section by noting that none of these novel and still hypothetical polynitrogen species corresponds to any of the known allotropes of phosphorus. 

Because of the presence of two azide groups in positions adjacent to the ring nitrogen atoms in compound 13a, valence bond isomerization can result in formation of 6-azido-7-methyltetrazolo[l,5-A pyridazine 14a, 6-azido-8-methyltetrazolo[l,5-A pyridazine 15a, and the bis-tetrazole compound 16a. Calculations have been carried out by using hybrid density functional theory (B3LYP/6-311+G(d,p)) and complete basis set treatments (CBS-4M). All calculations revealed that the 8-methyl derivative 15a is the most stable isomer. Similar studies on the triazide derivative 13b, however, indicated that in this case the equilibrium is shifted to the 7-methyl form 14b. All these conclusions proved to be in entire agreement with the experimental findings (see Section 11.18.3.2.). 

Elimination of HI, which in the presence of an excess of IN3 can form hydrazoic acid, followed by its addition to the vinyl azides can give an intermediate triazide 75. The same compound could arise directly by substitution of one iodine atom by an azido group. The intermediate 75 has been considered to undergo a transannular reaction with homolytic cleavage of the weak C—I bond to form the radical 76, which loses a nitrogen atom to a radical 77. Combination of the two radicals leads to the 2-tetrazene 74 (equation 77). 

Knaggs [10] found that in the case of cyanuric triazide the distance between the pairs of nitrogen atoms is not the same, being 1.26 and 1.11 A respectively. Examination of the Raman spectrum of sodium azide solutions has confirmed the chain structure of hydrazoic acid (Langseth, Nielsen and Sorensen [11]). The same conclusion is drawn from investigations of the absorption spectrum in the infra-red (Herzberg et al. [12]). 

FIGURE 21.23 The van der Waals radii of the carbon and nitrogen atoms superimposed on an outiine of the moiecuiar structure of cyanuric triazide, C3N12, to show the voiume of space from which each moiecuie exciudes the others. Van der Waais forces in the moiecuiar crystai hoid the moiecuies in contact in a pattern that minimizes empty space. The thin white iines emphasize the 3-foid symmetry of the pattern. 

Cyanuric triazide is reduced by action of hydrogen sulfide to melamine— nitrogen is evolved and sulfur is precipitated [130]. It also decomposes in aqueous sodium hydroxide (0.1M) at 50 °C within several minutes yielding the sodium salt of cyanuric acid and sodium azide [46,52]. The substance is not irritating to the skin [17]. 

Cyanuric triazide decomposes explosively into molecular nitrogen and cyanogen (C2N2) when initiated tmder vacuum. Ignition in a confined space leads to formation of a black sooty residue (with high yield >91 wt.%) consisting of... 

---