Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Nitrogen pentafluoride
open-in-new
<h2 id="ionic-solid">Ionic solid</h2> <p>A variety of other <a href="/facts/Tetrafluoroammonium/eaXxRI80">tetrafluoroammonium</a> <a href="/facts/Salt_(chemistry)/lsSKwGpn">salts</a> are known ([NF4]+X−), as are <a href="/facts/Fluoride/LpqNMzwa">fluoride</a> salts of other ammonium cations ([NR4]+F−). </p><p>In 1966, W. E. Tolberg first synthesized a five-valent nitrogen compound of nitrogen and fluorine when tetrafluoroammonium compounds, tetrafluoroammonium hexafluoroantimonate(V) [NF4]+[SbF6]− and tetrafluoroammonium hexafluoroarsenate(V) [NF4]+[AsF6]− were made.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> In 1971 C. T. Goetschel announced the preparation of [NF4]+[BF4]− and also produced a white solid assumed to be tetrafluoroammonium fluoride ([NF4]+F−). This was made by treating nitrogen trifluoride and fluorine with 3 MeV electron radiation at 77 K. It decomposed above 143 K back into those ingredients.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Theoretical studies also show the ionic compound is very likely to decompose to <a href="/facts/Nitrogen_trifluoride/roXMdPhr">nitrogen trifluoride</a> and <a href="/facts/Fluorine/YUV0Fb8m">fluorine</a> gas.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p><p><a href="/facts/Karl_O._Christe/HdLvtTsn">Karl O. Christe</a> synthesised bis(tetrafluoroammonium) hexafluoronickelate(IV) ([NF4]+)2[NiF6]2−.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> He also prepared compounds with manganese, a fluorouranate, tetrafluoroammonium perchlorate [NF4]+ClO−4, tetrafluoroammonium fluorosulfate [NF4]+SO3F− and [N2F3]+ (trifluorodiazenium) salts.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> Christe attempted to make [NF4]+F− by <a href="/facts/Salt_metathesis_reaction/YpadY3lq">metathesis</a> of [NF4]+[SbF6]− with <a href="/facts/Caesium_fluoride/edycrnDL">CsF</a> in <a href="/facts/Hydrogen_fluoride/XfQxlqR6">HF</a> solvent at 20 °C. However, a variant, tetrafluoroammonium bifluoride hydrofluorates ([NF4]+[HF2]−·<i>n</i>HF), was produced. At room temperature it was a milky liquid, but when cooled, turned pasty. At −45 °C it had the form of a white solid. When reheated it frothed, giving off <a href="/facts/Fluorine/YUV0Fb8m">F2</a>, HF and <a href="/facts/Nitrogen_trifluoride/roXMdPhr">NF3</a> as <a href="/facts/Gases/hVVAoodV">gases</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> This has CAS number 71485-49-9.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p><p>I. J. Solomon believed that nitrogen pentafluoride was produced by the thermal decomposition of [NF4]+[AsF6]−, but experimental results were not reproduced.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p><p>Dominik Kurzydłowski and Patryk Zaleski-Ejgierd predict that a mixture of fluorine and nitrogen trifluoride under pressure between 10 and 33 GPa forms [NF4]+F− with <a href="/facts/Space_group/2XQx0J7M">space group</a> <i>R3m</i>. This is a high-pressure oxidation. Over 33 GPa it will form a stable ionic compound with formula ([NF4]+)2[NF6]−F− (bis(tetrafluoroammonium) hexafluoronitrate(V) fluoride) with space group <i>I4/m</i>. Over 151 GPa this is predicted to transform to [NF4]+[NF6]− (tetrafluoroammonium hexafluoronitrate(V)) with space group <i>P4/n</i>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> A NF5 molecular compound is not stable under any pressure conditions. </p> <h2 id="covalent-molecule">Covalent molecule</h2> <p> For a NF5 molecule to form, five fluorine atoms have to be arranged around a nitrogen atom. There is insufficient space to do this at typical nitrogen–fluorine covalent-bond lengths, so at least some bonds are forced to be longer. Calculations show that fragmentation to form NF4 and F radicals would have a <a href="/facts/Transition_state/34PsdqRd">transition state</a> barrier of around 66–84 kJ/mol (15.8–20.0 kcal/mol) and that this process is thermodynamically favourable (<a href="/facts/Exothermic/gCuSvpa4">exothermic</a>) by 38 kJ/mol (9 kcal/mol).<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> Nitrogen pentafluoride also violates the <a href="/facts/Octet_rule/X9jxSsos">octet rule</a> in which compounds with eight outer shell electrons are particularly stable.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Goetschel, C. T.; V. A. Campanile; R. M. Curtis; et al. (July 1972). "Preparation and properties of perfluoroammonium tetrafluoroborate, [NF4]+[BF4]−, and possible synthesis of nitrogen pentafluoride". Inorganic Chemistry. 11 (7): 1696–1701. doi:10.1021/ic50113a051. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Goetschel, C. T.; V. A. Campanile; R. M. Curtis; et al. (July 1972). "Preparation and properties of perfluoroammonium tetrafluoroborate, [NF4]+[BF4]−, and possible synthesis of nitrogen pentafluoride". Inorganic Chemistry. 11 (7): 1696–1701. doi:10.1021/ic50113a051. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Christe, Karl O.; William W. Wilson (December 1992). "Nitrogen pentafluoride: covalent NF5 versus ionic NF4+F− and studies on the instability of the latter". Journal of the American Chemical Society. 114 (25): 9934–9936. Bibcode:1992JAChS.114.9934C. doi:10.1021/ja00051a027. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Christe, Karl O. (September 1977). "Synthesis and characterization of bis(tetrafluoroammonium) hexafluoronickelate". Inorganic Chemistry. 16 (9): 2238–2241. doi:10.1021/ic50175a017. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Christe, Karl O. (23 May 1980). "Research Studies in NF4+ Salts" (PDF). Rockwell. Archived (PDF) from the original on December 27, 2015. Retrieved 23 February 2012. <a href="http://apps.dtic.mil/dtic/tr/fulltext/u2/a086981.pdf" target="_blank">http://apps.dtic.mil/dtic/tr/fulltext/u2/a086981.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Christe, Karl O. (23 May 1980). "Research Studies in NF4+ Salts" (PDF). Rockwell. Archived (PDF) from the original on December 27, 2015. Retrieved 23 February 2012. <a href="http://apps.dtic.mil/dtic/tr/fulltext/u2/a086981.pdf" target="_blank">http://apps.dtic.mil/dtic/tr/fulltext/u2/a086981.pdf</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Tetrafluoroammonium bifluoride <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Christe, Karl O.; William W. Wilson; Gary J. Schrobilgen; et al. (March 1998). "On the existence of pentacoordinated nitrogen". Inorganic Chemistry. 27 (5): 789–790. doi:10.1021/ic00278a009. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Kurzydłowski, Dominik; Zaleski-Ejgierd, Patryk (3 November 2016). "Hexacoordinated nitrogen(V) stabilized by high pressure". Scientific Reports. 6: 36049. Bibcode:2016NatSR...636049K. doi:10.1038/srep36049. PMC 5093683. PMID 27808104. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5093683" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5093683</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Holger F. Bettinger; Paul v. R. Schleyer; Henry F. Schaefer III (27 October 1998). "NF5 — Viable or Not?". Journal of the American Chemical Society. 120 (44): 11439–11448. Bibcode:1998JAChS.12011439B. doi:10.1021/ja9813921. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Lewars, Errol G. (3 November 2008). "Nitrogen Pentafluoride and Related Compounds". Modeling marvels: computational anticipation of novel molecules. Springer. pp. 53–67. doi:10.1007/978-1-4020-6973-4_4. ISBN 978-1-4020-6972-7. <a href="978-1-4020-6972-7" target="_blank">978-1-4020-6972-7</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> </ol>