Nitrogen pentafluoride

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Nitrogen pentafluoride
Names
IUPAC name
Nitrogen pentafluoride
Identifiers
3D model (JSmol)
  • InChI=1S/F4N.FH/c1-5(2,3)4;/h;1H/q+1;/p-1
    Key: HGLYTTWJVOQBNH-UHFFFAOYSA-M
  • InChI=1S/F5N/c1-6(2,3,4)5
    Key: IFPFUYZWFMFDTL-UHFFFAOYSA-N
  • ionic:F[N+](F)(F)F.[F-]
  • covalent:FN(F)(F)(F)F
Properties
NF5
Molar mass 108.999 g·mol−1
Structure
trigonal bipyramidal
0 D
Related compounds
Other cations
Phosphorus pentafluoride
Arsenic pentafluoride
Antimony pentafluoride
Bismuth pentafluoride
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Nitrogen pentafluoride is a theoretical compound of nitrogen and fluorine with the chemical formula N F 5. It is hypothesized to exist based on the existence of the pentafluorides of the atoms below nitrogen in the periodic table, such as phosphorus pentafluoride. Theoretical models of the nitrogen pentafluoride molecule are either a trigonal bipyramidal covalently bound molecule with symmetry group D3h, or [NF4]+F− (tetrafluoroammonium fluoride), which would be an ionic solid.

Contents

Ionic solid

A variety of other tetrafluoroammonium salts are known ([NF4]+X−), as are fluoride salts of other ammonium cations ([NR4]+F−).

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. [2] 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. [2] Theoretical studies also show the ionic compound is very likely to decompose to nitrogen trifluoride and fluorine gas. [3]

Karl O. Christe synthesised bis(tetrafluoroammonium) hexafluoronickelate(IV) ([NF4]+)2[NiF6]2−. [4] He also prepared compounds with manganese, a fluorouranate, tetrafluoroammonium perchlorate [NF4]+ClO−4, tetrafluoroammonium fluorosulfate [NF4]+SO3F− and [N2F3]+ (trifluorodiazenium) salts. [5] Christe attempted to make [NF4]+F− by metathesis of [NF4]+[SbF6]− with CsF in HF solvent at 20 °C. However, a variant, tetrafluoroammonium bifluoride hydrofluorates ([NF4]+[HF2]−·nHF), 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 F2, HF and NF3 as gases. [5] This has CAS number 71485-49-9. [6]

I. J. Solomon believed that nitrogen pentafluoride was produced by the thermal decomposition of [NF4]+[AsF6]−, but experimental results were not reproduced. [7]

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 space group R3m. 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 I4/m. Over 151 GPa this is predicted to transform to [NF4]+[NF6]− (tetrafluoroammonium hexafluoronitrate(V)) with space group P4/n. [8] A NF5 molecular compound is not stable under any pressure conditions.

Covalent molecule

Possible structure of NF5 (left) and analogous fluorohydrides Nitrogen pentafluoride possible structures.jpg
Possible structure of NF5 (left) and analogous fluorohydrides

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 transition state barrier of around 66–84 kJ/mol (15.8–20.0 kcal/mol) and that this process is thermodynamically favourable (exothermic) by 38 kJ/mol (9 kcal/mol). [9] Nitrogen pentafluoride also violates the octet rule in which compounds with eight outer shell electrons are particularly stable. [10]

Related Research Articles

In chemistry, noble gas compounds are chemical compounds that include an element from the noble gases, group 18 of the periodic table. Although the noble gases are generally unreactive elements, many such compounds have been observed, particularly involving the element xenon.

In chemistry, an interhalogen compound is a molecule which contains two or more different halogen atoms and no atoms of elements from any other group.

<span class="mw-page-title-main">Oxygen fluoride</span> Any binary compound of oxygen and fluorine

Oxygen fluorides are compounds of elements oxygen and fluorine with the general formula OnF2, where n = 1 to 6. Many different oxygen fluorides are known:

<span class="mw-page-title-main">Chlorine pentafluoride</span> Chemical compound

Chlorine pentafluoride is an interhalogen compound with formula ClF5. This colourless gas is a strong oxidant that was once a candidate oxidizer for rockets. The molecule adopts a square pyramidal structure with C4v symmetry, as confirmed by its high-resolution 19F NMR spectrum. It was first synthesized in 1963.

<span class="mw-page-title-main">Xenon difluoride</span> Chemical compound

Xenon difluoride is a powerful fluorinating agent with the chemical formula XeF
2, and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherwise stable in storage. Xenon difluoride is a dense, colourless crystalline solid.

<span class="mw-page-title-main">Selenium tetrafluoride</span> Chemical compound

Selenium tetrafluoride (SeF4) is an inorganic compound. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses (fluorination of alcohols, carboxylic acids or carbonyl compounds) and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas.

Bromine compounds are compounds containing the element bromine (Br). These compounds usually form the -1, +1, +3 and +5 oxidation states. Bromine is intermediate in reactivity between chlorine and iodine, and is one of the most reactive elements. Bond energies to bromine tend to be lower than those to chlorine but higher than those to iodine, and bromine is a weaker oxidising agent than chlorine but a stronger one than iodine. This can be seen from the standard electrode potentials of the X2/X− couples (F, +2.866 V; Cl, +1.395 V; Br, +1.087 V; I, +0.615 V; At, approximately +0.3 V). Bromination often leads to higher oxidation states than iodination but lower or equal oxidation states to chlorination. Bromine tends to react with compounds including M–M, M–H, or M–C bonds to form M–Br bonds.

Nitrogen fluorides are compounds of chemical elements nitrogen and fluorine. Many different nitrogen fluorides are known:

<span class="mw-page-title-main">Dioxygenyl</span> Chemical compound

The dioxygenyl ion, O+
2, is a rarely-encountered oxycation in which both oxygen atoms have a formal oxidation state of +⁠1/2⁠. It is formally derived from oxygen by the removal of an electron:

Arsenic trifluoride is a chemical compound of arsenic and fluorine with the chemical formula AsF3. It is a colorless liquid which reacts readily with water.

<span class="mw-page-title-main">Tetrafluoroammonium</span> Chemical compound

The tetrafluoroammonium cation is a positively charged polyatomic ion with chemical formula NF+
4. It is equivalent to the ammonium ion where the hydrogen atoms surrounding the central nitrogen atom have been replaced by fluorine. Tetrafluoroammonium ion is isoelectronic with tetrafluoromethane CF
4, trifluoramine oxide ONF
3, tetrafluoroborate BF−
4 anion and the tetrafluoroberyllate BeF2−
4 anion.

<span class="mw-page-title-main">Chloryl</span> Ion

In chemistry, chloryl refers to a triatomic cation with chemical formula ClO+
2. This species has the same general structure as chlorite (ClO−
2) but it is electronically different, with chlorine having a +5 oxidation state (rather than the +3 of chlorite). This makes it a rare example of a positively charged oxychloride. Chloryl compounds, such as FClO
2 and [ClO2][RuF6], are all highly reactive and react violently with water and most organic compounds.

<span class="mw-page-title-main">Potassium hexafluoronickelate(IV)</span> Chemical compound

Potassium hexafluoronickelate(IV) is an inorganic compound with the chemical formula K
2NiF
6. It can be produced through the reaction of potassium fluoride, nickel dichloride, and fluorine.

Fluorine forms a great variety of chemical compounds, within which it always adopts an oxidation state of −1. With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. Fluoride may act as a bridging ligand between two metals in some complex molecules. Molecules containing fluorine may also exhibit hydrogen bonding. Fluorine's chemistry includes inorganic compounds formed with hydrogen, metals, nonmetals, and even noble gases; as well as a diverse set of organic compounds. For many elements the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others the highest oxidation states of oxides and fluorides are always equal.

<span class="mw-page-title-main">Karl O. Christe</span> German inorganic chemist

Karl Otto Christe is an inorganic chemist. He is the best reference in respectful handling of a huge number of extremely reactive components and his extensive experience in fluorine chemistry earned him the title of 'The Fluorine God'. His research covers fluorine chemistry of nitrogen and halogens and the synthesis of new energetic materials.

Difluoroamino sulfur pentafluoride is a gaseous chemical compound of fluorine, sulfur, and nitrogen. It is unusual in having a hexa-coordinated sulfur atom with a link to nitrogen. Other names for this substance include difluoro(pentafluorosulfur)amine, pentafluorosulfanyldifluoramine, and pentafluorosulfanyl N,N-difluoramine.

<span class="mw-page-title-main">Trifluoramine oxide</span> Chemical compound

Trifluoramine oxide or Nitrogen trifluoride oxide (F3NO) is an inorganic molecule with strong fluorinating powers.

<span class="mw-page-title-main">Chlorine trifluoride oxide</span> Chemical compound

Chlorine oxide trifluoride or chlorine trifluoride oxide is a corrosive liquid molecular compound with formula ClOF3. It was developed secretly as a rocket fuel oxidiser.

<span class="mw-page-title-main">Nitrogen pentahydride</span> Chemical compound

Nitrogen pentahydride, also known as ammonium hydride is a hypothetical compound with the chemical formula NH5. There are two theoretical structures of nitrogen pentahydride. One structure is trigonal bipyramidal molecular geometry type NH5 molecule. Its nitrogen atom and hydrogen atoms are covalently bounded, and its symmetry group is D3h. Another predicted structure of nitrogen pentahydride is an ionic compound, composed of an ammonium ion and a hydride ion (NH4+H−). Until now, no one has synthesized this substance, or proved its existence, and related experiments have not directly observed nitrogen pentahydride. It is only speculated that it may be a reactive intermediate based on reaction products. Theoretical calculations show this molecule is thermodynamically unstable. The reason might be similar to the instability of nitrogen pentafluoride, so the possibility of its existence is low. However, nitrogen pentahydride might exist in special conditions or high pressure. Nitrogen pentahydride was considered for use as a solid rocket fuel for research in 1966.

<span class="mw-page-title-main">Hexafluoroarsenate</span> Chemical compound

The hexafluoroarsenate anion is a chemical species with formula AsF−6. Hexafluoroarsenate is relatively inert, being the conjugate base of the notional superacid hexafluoroarsenic acid.

References

  1. ↑ Jäger, Susanne; von Jouanne, Jörn; Keller-Rudek, Hannelore; et al. (1986). F Fluorine: Compounds with Oxygen and Nitrogen. Gmelin Handbook of Inorganic Chemistry. Vol. 4. Berlin: Springer. p. 163. doi:10.1007/978-3-662-06339-2. ISBN   978-3-662-06341-5 . Retrieved 29 August 2015.
  2. 1 2 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.
  3. ↑ 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. doi:10.1021/ja00051a027.
  4. ↑ Christe, Karl O. (September 1977). "Synthesis and characterization of bis(tetrafluoroammonium) hexafluoronickelate". Inorganic Chemistry. 16 (9): 2238–2241. doi:10.1021/ic50175a017.
  5. 1 2 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.
  6. ↑ Tetrafluoroammonium bifluoride
  7. ↑ 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.
  8. ↑ 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. Open Access logo PLoS transparent.svg
  9. ↑ 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. doi:10.1021/ja9813921.
  10. ↑ 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.
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