Nitrogen triiodide: Difference between revisions
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'''Nitrogen triiodide''' is the [[inorganic compound]] with the formula [[nitrogen|N]][[Iodine|I]]<sub>3</sub>. It is an extremely sensitive [[contact explosive]]: small quantities explode with a gunpowder-like snap when touched even lightly, releasing a purple cloud of iodine vapor. NI<sub>3</sub> has a complex structural chemistry that is |
'''Nitrogen triiodide''' is the [[inorganic compound]] with the formula [[nitrogen|N]][[Iodine|I]]<sub>3</sub>. It is an extremely sensitive [[contact explosive]]: small quantities explode with a gunpowder-like snap when touched even lightly, releasing a purple cloud of iodine vapor. NI<sub>3</sub> has a complex structural chemistry that is difficult to study because of the instability of the derivatives. |
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==Structure of NI<sub>3</sub> and its derivatives== |
==Structure of NI<sub>3</sub> and its derivatives== |
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Revision as of 16:30, 31 May 2010
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| Names | |||
|---|---|---|---|
| IUPAC name
triiodoamine
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| Other names
nitrogen iodide, triiodine nitride
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| Identifiers | |||
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |||
| NI3 | |||
| Molar mass | 394.7201 g/mol | ||
| Appearance | red solid | ||
| no | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Nitrogen triiodide is the inorganic compound with the formula NI3. It is an extremely sensitive contact explosive: small quantities explode with a gunpowder-like snap when touched even lightly, releasing a purple cloud of iodine vapor. NI3 has a complex structural chemistry that is difficult to study because of the instability of the derivatives.
Structure of NI3 and its derivatives
Nitrogen triiodide was first characterized by X-ray crystallography in 1990 when it was prepared by an ammonia-free route. Boron nitride reacts with iodine fluoride in trichlorofluoromethane at −30 °C to produce pure NI3 in low yield.[1] NI3 is pyramidal (C3v molecular symmetry), as are the other nitrogen trihalides as well as ammonia.[2]
The material that is usually called "nitrogen triiodide" is prepared by the reaction of iodine with ammonia. When this reaction is conducted at low temperatures in anhydrous ammonia, the initial product is NI3·(NH3)5, but this material loses some ammonia upon warming to give the 1:1 adduct NI3·(NH3). This adduct was first reported by Bernard Courtois in 1812, and its formula was finally determined in 1905 by Silberrad.[3] Its solid state structure consists of chains of -NI2-I-NI2-I-NI2-I-... Ammonia molecules are situated between the chains. When kept cold in the dark and damp with ammonia, NI3·(NH3) is stable.
Decomposition and explosiveness
The instability of NI3 and NI3NH3 can be attributed to the great stability of N2. Nitrogen triiodide has no practical commercial value due to its extreme shock sensitivity, making it difficult to store, transport, and utilize for controlled explosions. Whereas pure nitroglycerin is also highly shock-sensitive and powerful, it was only due to phlegmatizers that its shock sensitivity was reduced and it became safer to handle and transport as dynamite.
The decomposition of NI3 proceeds as follows to give nitrogen gas and iodine:
- 2 NI3 (s) → N2 (g) + 3 I2 (g) (–290 kJ/mol)
However, the dry material is a contact explosive, decomposing approximately as follows:[2]
- 8 NI3NH3 → 5 N2 + 6 NH4I + 9 I2
Consistent with this equation, these explosions leave orange-to-purple stains of iodine, which can be removed with sodium thiosulfate solution. An alternate method of stain removal is to simply allow the iodine time to sublimate. Small amounts of nitrogen triiodide are sometimes synthesized as a demonstration to high school chemistry students or as an act of "chemical magic".[4] To highlight the sensitivity of the compound, it is usually detonated by touching it with a feather but even the slightest air current or other movement can cause detonation. Nitrogen triiodide is also notable for being the only known chemical explosive that detonates when exposed to alpha particles and nuclear fission products.[5]
References
- ^ Tornieporth-Oetting, I.; Klapötke, T. (1990). "Nitrogen Triiodide". Angewandte Chemie International Edition. 29: 677–679. doi:10.1002/anie.199006771.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ Silberrad, O. "On the Constitution of Nitrogen Triiodide" Journal of the Chemistry Society 1905, volume 87, pages 55-66. doi:10.1039/CT9058700055
- ^ Ford, L. A. and Grundmeier, E. W. Chemical Magic. Dover, 1993, p. 76. ISBN 0486676285
- ^ Bowden, F. P. Initiation of explosion by neutrons, α-particles, and fission products. Proc. Roy. Soc. (London) 1958, A246, 216-19.