Azide forms both covalent and ionic compounds with metals. Sodium azide, NaN3, is a salt that is widely used as the propellant in airbags. Covalent azides are numerous, an example being [Co(NH3)5N3]Cl2. A metal-organic azide is trimethylsilylazide, which is sometimes used as an anhydrous source of N3−.
Azides in biochemistry
The azide anion is toxic, inhibiting the function of cytochrome c oxidase by binding irreversibly to the heme cofactor, in a process similar to that of cyanide. Azide salts are also used in studies of mutagenesis.
In reaction with water or Brønsted acids the highly toxic and explosive hydrogen azide is released.
It has been reported that sodium azide and polymer-bound azide reagents react with dichloromethane and chloroform to form di- and triazidomethane resp., which are both unstable in high concentrations in solution. Various devastating explosions were reported while reaction mixtures were being concentrated on a rotary evaporator. The hazards of diazidomethane (and triazidomethane) have been well documented by A. Hassner et al. .
Heavy-metal azides that are highly explosive under pressure or shock are formed when solutions of sodium azide or HN3 vapors come into contact with heavy metals or their salts. Heavy-metal azides can accumulate under certain circumstances, for example, in metal pipelines and on the metal components of diverse equipment (rotary evaporators, freezedrying equipment, cooling traps, water baths, waste pipes), and thus lead to violent explosions. Some organic and other covalent azides are classified as highly explosive and toxic (inorganic azides as neurotoxins; azide ions as cytochrome c oxidase (COX) inhibitors).
Solid iodoazide is explosive and should not be prepared in the absence of solvent..
^Review: S. Bräse, C. Gil, K. Knepper, V. Zimmermann, Angew. Chem. 2005, 117, 5320-5374; Angew. Chem. Int. Ed. 2005, 44, 5188-5240.
^ Tornieporth-Oetting, I. C.; Klapoetke, T. M. "Covalent Inorganic Azides" Angewandte Chemie, International Edition in English (1995), volume 34, pages 511-20. AN 1995:483017
^An efficient synthesis of γ-imino- and γ-amino-β-enamino esters Mangelinckx, S.; Van Vooren, P.; De Clerck, D.; Fülöp, F.; De Kimpea, N. Arkivoc JC-1560E 2005 Online Article