Other azides

The crystal structures of numerous molecular azides and coordinative azides (besides the valence metal azides) have been investigated in recent years. The structures of the azide groups in these crystals and pertinent references are summarized in Table IV. 

The two cation groups in the [(NH2)2C(N3)]C1 and [C(N3)3]SbCl6 crystals are similar in chemical bonding. The azide group of the [(NH2)2C(N3)] cation is strongly asymmetric with the N-N distances comparable to the normal covalent azide. However, the three azide groups in the [C(N3)3] cation show unusually extreme asymmetry. The three azide groups of the cation are bonded to the 

Compound space group Unit cell Z Ni-Nj N2-N3 R-Ni R-N-N References 

The azide groups in the five-coordinate compounds, [As(C6H5)4] [Fe(N3)5] and Cu(Br)(N3)[HN(CH2)2N(C2H5)2], are coordinated to the metal atom (Fe or Cu) by one terminal nitrogen of each. In spite of the asymmetric coordinations, these azide groups are symmetric within the limit of experimental error, which is very unusual. 

The determination of the crystal structure of the metal azides represents the foundation upon which the understanding of their pseudostabihty rests. Great strides have been made in recent years in the elucidation of electronic and vibrational behavior, as detailed in this book, which have paralleled the advances made in structure determinations. 

Caesium azide melts with a little decomposition ( 1%) at 598 K. There is slow decomposition of the solid when large amounts of NiO are present [714], Observations on the photolyses of RbN3 and CsN3 have been discussed [715] with reference to the pyrolyses of other alkali azides. 

The kinetic observations reported by Young [721] for the same reaction show points of difference, though the mechanistic implications of these are not developed. The initial limited ( 2%) deceleratory process, which fitted the first-order equation with E = 121 kJ mole-1, is (again) attributed to the breakdown of superficial impurities and this precedes, indeed defers, the onset of the main reaction. The subsequent acceleratory process is well described by the cubic law [eqn. (2), n = 3], with E = 233 kJ mole-1, attributed to the initial formation of a constant number of lead nuclei (i.e. instantaneous nucleation) followed by three-dimensional growth (P = 0, X = 3). Deviations from strict obedience to the power law (n = 3) are attributed to an increase in the effective number of nuclei with reaction temperature, so that the magnitude of E for the interface process was 209 kJ mole-1. 

The influence of pre-irradiation on a-PbN6 decomposition kinetics was studied by Jach [722]. The initial acceleratory process in untreated solid [eqn. (2), n = 2] was ascribed to surface and three-dimensional growth 

Characteristically, the mechanisms formulated for azide decompositions involve [693,717] exciton formation and/or the participation of mobile electrons, positive holes and interstitial ions. Information concerning the energy requirements for the production, mobility and other relevant properties of these lattice imperfections can often be obtained from spectral data and electrical measurements. The interpretation of decomposition kinetics has often been profitably considered with reference to rates of photolysis. Accordingly, proposed reaction mechanisms have included consideration of trapping, transportation and interactions between possible energetic participants, and the steps involved can be characterized in greater detail than has been found possible in the decompositions of most other types of solids. 

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Potential hazards arising from slow formation of explosive azides from prolonged contact of halogenated solvents with metallic or other azides are outlined. 

Diphenyl phosphorszldate can be replaced with diethyl phosphorazidate in the above procedure. Use of other azides such as p-toluenesulfonyl azide, p-methoxybenzyloxycarbonyl azide, diphenylphosphinic azide, or diphenylthio-phosphinic azide is less satisfactory. No reaction occurs when trimethylsilyl azide, dimethylthiophosphinic azide, or alkaline azides are used, while decomposition of formed trimethylsilyldiazomethane seems to occur when... 

For other azides (in the solid state) the following bands were found in the reflection spectrum ... 

As shown by the investigations of a number of authors, irradiation of lead azide (and other azides) with a-particles, X-rays and y-rays does not cause explosion (Ha issinsky and Walden [89] Gunther, Lepin and Andreyev [90]). However, it produces a slow decomposition of lead azide, according to Kaufman [91]. 

The explosive properties of sodium, calcium, strontium and barium azides have been investigated at the Chemisch-Technische Reichsanstalt [135]. These azides differ markedly from lead, silver and cupric azides in that they show none of the properties of primary explosives. All three may be ignited by a spark, a glowing wire or the flame of blackpowder. Calcium azide bums most rapidly and has distinctly marked explosive properties. Larger quantities of it may explode when ignited in a closed tin, while strontium and barium merely bum violently. Calcium azide detonates under the influence of a detonating cap. The sodium azide does not decompose in these conditions. The other azides show weak decomposition under the influence of a standard (No. 3) detonator. Their most important properties are tabulated below. 

See. for example. Spagnolo Zamrato, Gronowitz J. Org. Chem. 1982, 47. 3177 Reed Snieckus Tetrahedron Lett. 1983,24, 3795. For other azides, see Hassner Munger Belinka Tetrahedron Lett. 1982, 23, 699 Mori Aovama Shioiri Tetrahedron Lett. 1984, 25, 429. 

According to Ebler (Ref 5) Ba azide is not decompd by exposure to radium. Gyunter et al (Ref 15) also found that, unlike other azides, Ba azide is not decompd by X-rays of radium. X-rays of less than 0.7 A° also have no effect while soft X-rays produce a weak blue fluorescence. By using a Hadding tube,... 

Uses of Sodium Azide. The principal use of NaN, in the expl ind is in the prepn of alkali alkaline earth and other azides (Refs 37,38, 42,96,113,201,% others) (See Lead Azide, Plant Manufacture, etc). Meissner (Ref 44) used equiv quants of NaN, and a heavy metal salt, such as Pb acetate, for the continuous prepn of LA. Matter (Ref 33) found that NaN, was freed from carbonates by the addn of aq... 

Petrikaln (Ref 7) photographed the spectra of Zn(N3)a and other azides. With the azides of Ca, Sr and Ba, not only triplet system lines but also those of the singlet system were emitted. Zn(N3)a emitted only triplet system lines of the diffuse and sharp series. In addn the oxide bands were present in all the spectra. Kahovec Kohlrausch (Ref 13) detd the Raman spectra of basic zinc azide crysts. 

The effect of UV radiation on other azides was conducted by Muller and Brous on Na azide (Ref 8), by Garner and Maggs on Ba and Sr azides (Ref 16), by Mott on metallic azides (Ref 17), and by Boldyrev and Skorik on Ag and Ba azides (Ref 144). With Na, Sr and Ba azides, each are decompd by UV light at room temp and the thermal decompn of these materials is accelerated by pre-irradiation. Boldyrev et al found that irradiating Ag azide with UV light or X-rays at the instant of decompn had no effect on the rate of its thermal decompn... 

Besides the ring-forming reactions already described, trimethylsilyl azide (14) gives an access to a great variety of products. As an important property the excellent stability of 14 must be noted228,229> which makes it more advantageous to employ TMSA (14) instead of other azides. 

Some compounds having the azide group are used in explosives. Cyanuric triazide (I) is particularly sensitive and powerful. Other azides... 

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