Nitrogen triiodide 241564 217775305 2008-06-07T16:47:37Z 71.126.96.232 {{Chembox new | Name = Nitrogen triiodide | ImageFile = Nitrogen-iodide-2D.png | ImageSize = 150px | ImageName = Nitrogen triiodide (structural formula) | ImageFile1 = Nitrogen-triiodide-3D-balls.png | ImageSize1 = 150px | ImageName1 = Nitrogen triiodide | Section1 = {{Chembox Identifiers | CASNo = 13444-85-4 }} | Section2 = {{Chembox Properties | Formula = NI<sub>3</sub> | Shock_sensitivity = Extremely high / high when wet | Friction_sensitivity = Extremely high / high when wet | MolarMass = 394.77 g/mol | Density = ? g/cm<sup>3</sup> | Solvent = other solvents | SolubleOther = Decomposes | MeltingPt = ''N/A'' | BoilingPt = sublimes at -20 °C }} | Section8 = {{Chembox Related | Function = [[halide]]s | OtherFunctn = [[Nitrogen trifluoride]]<br />[[Nitrogen trichloride]]<br />[[Nitrogen tribromide]] | Function = [[iodide]]s | OtherFunctn = [[Phosphorus triiodide]]<br />[[Arsenic triiodide]]}} }} '''Nitrogen triiodide''', also called '''nitrogen iodide''', more correctly, '''triiodine nitride''', is the [[chemical 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 has required relatively heroic efforts to elucidate because of the instability of the derivatives. Nitrogen triiodide has no practical commercial value due to its extreme shock sensitivity, making it difficult to store, transport, and utilize for controlled explosions. While 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]]. ==Decomposition== The decomposition of NI<sub>3</sub> proceeds via the following reaction: :2NI<sub>3</sub>(s) → N<sub>2</sub>(g) + 3I<sub>2</sub>(g) ΔH = –290 kJ/mol ==Structure of NI<sub>3</sub> and its derivatives== Nitrogen triiodide is a dark red compound, 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 NI<sub>3</sub> in low yield.<ref>Tornieporth-Oetting, I.; Klapötke, T. ''Angewandte Chemie International Edition in English," 1990, volume 29, pages 677-679. [http://dx.doi.org/10.1002/anie.199006771]</ref> NI<sub>3</sub> is pyramidal (C<sub>3v</sub> [[molecular symmetry]]), as are the other nitrogen trihalides as well as [[ammonia]].<ref name=Holleman>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref> 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 NI<sub>3</sub>·(NH<sub>3</sub>)<sub>5</sub>, but this material loses some ammonia upon warming to give the 1:1 [[adduct]] NI<sub>3</sub>·(NH<sub>3</sub>). This adduct was first reported by [[Bernard Courtois]] in [[1812]], and its formula was finally determined in 1905 by Silberrad.<ref>Silberrad, O. "On the Constitution of Nitrogen Triiodide" ''Journal of the Chemistry Society'' 1905, volume 87, pages 55-66. DOI: 10.1039/CT9058700055</ref> Its solid state structure consists of chains of -NI<sub>2</sub>-I-NI<sub>2</sub>-I-NI<sub>2</sub>-I-... Ammonia molecules are situated between the chains. In the dark and kept cold and damp with ammonia, NI<sub>3</sub>·(NH<sub>3</sub>) is stable. The dry material is, however a contact explosive decomposing according to the following equation:<ref name=Holleman/> : 8NI<sub>3</sub>NH<sub>3</sub> → 5 N<sub>2</sub> + 6 NH<sub>4</sub>I + 9 I<sub>2</sub> The instability of NI<sub>3</sub> itself or NI<sub>3</sub>NH<sub>3</sub> can be attributed to the great stability of N<sub>2</sub>. ==Nitrogen triiodide in classroom demonstrations and popular culture== *Small amounts of nitrogen triiodide are sometimes synthesized as a demonstration to high school chemistry students or as an act of "chemical magic".<ref>Ford, L. A. and Grundmeier, E. W. ''Chemical Magic''. Dover, '''1993''', p. 76. ISBN 0486676285</ref> 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 explosive that detonates when exposed to [[alpha particles]] and [[nuclear fission]] products.<ref>Bowden, F. P. Initiation of explosion by neutrons, α-particles, and fission products. ''Proc. Roy. Soc.'' (London) '''1958''', ''A246'', 216-19.</ref> *NI<sub>3</sub>·NH<sub>3</sub> explosions leave orange-to-purple [[iodine]] stains that can be removed by [[sodium thiosulfate]] solution. *Nitrogen triiodide is the contact explosive used in ''[[Brainiac: Science Abuse]]'', named "Peter Logan's Exploding Paste" on the show, although the details of its production are not mentioned for safety purposes. *In [[Robert_A._Heinlein|Robert Heinlein]]'s novel ''[[Farnham's Freehold]]'', the eponymous Hugh Farnham uses nitrogen triiodide (made from ammonia and iodine) as a blasting powder. ==References== <references /> ==External links== *[http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA0/MOVIES/NI3IOD.html See the explosion (requires the Quicktime plugin)] *[http://www.chm.bris.ac.uk/motm/ni3/ni3j.htm Nitrogen Tri-Iodide - explains why the compound is explosive] *[http://www.youtube.com/watch?v=2KlAf936E90 Nitrogen Tri-Iodide Detonation on Youtube] [[Category:Nitrogen compounds]] [[Category:Iodides]] [[Category:Nonmetal halides]] [[Category:Explosive chemicals]] [[Category:Pyrotechnic chemicals]] [[da:Nitrogentriiodid]] [[de:Iodstickstoff]] [[it:Triioduro di azoto]] [[lv:Joda nitrīds]] [[lt:Azoto trijodidas]] [[nl:Stikstoftrijodide]] [[ja:ヨウ化窒素]] [[no:Nitrogentrijodid]] [[pl:Trijodek azotu]] [[pt:Triiodeto de nitrogênio]] [[ru:Нитрид трииода]] [[sk:Jododusík]] [[fi:Jodityppi]] [[zh:三碘化氮]]