Difluoroamino sulfur pentafluoride

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Difluoroamino sulfur pentafluoride
Difluoroamino sulfur pentafluoride.svg
[1]
Names
Other names
  • Difluoro(pentafluorosulfur)amine
  • Pentafluorosulfanyldifluoramine
  • Pentafluorosulfanyl N,N-difluoramine
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1/F7NS/c1-8(2)9(3,4,5,6)7
    Key: QCVDQGPCVDNCIO-UHFFFAOYSA-N
  • FN(F)S(F)(F)(F)(F)F
Properties
SF5NF2
Molar mass 179.062 g/mol
AppearanceColourless gas
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.

Contents

Properties

Difluoroamino sulfur pentafluoride is a colourless gas at room temperature. [3] The molecule is shaped as a tetragonal bipyramid around the sulfur atom. [3]

To within half a degree the boiling point is -17.5 °C. [3]

Difluoroamino sulfur pentafluoride is stable at room temperature, but decomposes on the timescale of hours at 80 °C. Decomposition results in sulfur tetrafluoride and nitrogen trifluoride. [3] It is not stable above 220 °C. [4] It is stable with water or stainless steel. [4]

When stored in quartz and exposed to ultraviolet light, it decomposes slightly and reacts with silica to make SF4, N2F4, SF6, NF3, SO2F2, SOF4 and N2O. [3]

The bond between sulfur and nitrogen is quite weak with a dissociation energy of 50 kcal/mol. [5]

The infrared spectrum contains strong absorption bands around 885, 910, and 950 cm−1 due to the bonds with fluorine. If a strong irradiation at 910 cm−1 with a laser takes place the molecules can be disrupted to form S2F10, SF4 and N2F4. By adjusting the frequency of a laser, the break up can be made isotope selective, and also the S2F10 can be broken up by another nearby frequency. [5]

The fluorine atoms attached to the sulfur are attached at close to 90° from each other, and the four around the equator are also at 90° from the nitrogen sulfur bond. The angle subtended by fluorine atoms on the nitrogen atom is about 98°, and the sulfur-nitrogen-fluorine angle is about 111°. The distance between sulfur and the four equatorial fluorine atoms is 1.545 Å. The axial fluorine to sulfur distance is 1.556 Å. Nitrogen sulfur distance is about 1.696 Å. The fluorine-nitrogen bond is the shortest in the molecule at 1.378 Å. [1]

Preparation

Difluoroamino sulfur pentafluoride has been prepared by irradiating a mixture of dinitrogen tetrafluoride and sulfur tetrafluoride with ultraviolet light.

N2F4 + 2 SF4 → 2 SF5NF2. [3]

This preparation also works with a mixture of dinitrogen tetrafluoride and sulfur chloride pentafluoride. Formation requires the appearance of the SF5 radical and chlorine atoms, as well as the nitrogen difluoride radical. [3]

Another way to make difluoroamino sulfur pentafluoride is by heating dinitrogen tetrafluoride and sulfur. This results in the temporary formation of nitrogen difluoride. However the yield is only around 6%, and mostly sulfur tetrafluoride is formed. [3] Yet other substrates for dinitrogen tetrafluoride are disulfur decafluoride or sulfur dioxide or thiophosgene in an electric discharge. [6]

A corona discharge in a sulfur hexafluoride, nitrogen mixture produces a small amount of difluoroamino sulfur pentafluoride. This is important as high voltage equipment is often insulated with this gas combination. [7]

Pentafluorosulfanylamine reacts with fluorine gas to yield difluoroamino sulfur pentafluoride: [8]

SF5NH2 + 2 F2 → SF5NF2 + 2 HF

Reactions

Difluoroamino sulfur pentafluoride reacts with Lewis acids like KrF+AsF6− at -31 °C to yield SF6, Kr, NF3 and solid N2F+AsF6−. With AsF5 at -196 °C (as liquid) it produces solid N2F+AsF6−, SF6 and trans-N2F2. Similar products also come from room temperature reactions. [9]

Use

There is a Russian patent to use a combination of alkenes and difluoroamino sulfur pentafluoride as a rocket fuel. [10]

Related substances include fluoroimidotetrafluorosulfur F4S=NF and (SF5)2NF. [11] A tertiary amine exists with formula (SF5)3N.

Other variant substitutions on the nitrogen atom yield SF5NFCl, SF5NHF, SF5NCl2 and SF5NH2.

Related Research Articles

Disulfur decafluoride Chemical compound

Disulfur decafluoride (S2F10) is a chemical compound discovered in 1934 by Denbigh and Whytlaw-Gray. Each sulfur atom of the S2F10 molecule is octahedral, and surrounded by five fluorine atoms. S2F10 is highly toxic, with toxicity four times that of phosgene.

Sulfur tetrafluoride Chemical compound

Sulfur tetrafluoride is the chemical compound with the formula SF4. It is a colorless corrosive gas that releases dangerous HF upon exposure to water or moisture. Despite these unwelcome characteristics, this compound is a useful reagent for the preparation of organofluorine compounds, some of which are important in the pharmaceutical and specialty chemical industries.

Selenium tetrafluoride 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.

Krypton difluoride Chemical compound

Krypton difluoride, KrF2 is a chemical compound of krypton and fluorine. It was the first compound of krypton discovered. It is a volatile, colourless solid. The structure of the KrF2 molecule is linear, with Kr−F distances of 188.9 pm. It reacts with strong Lewis acids to form salts of the KrF+ and Kr
2F+
3 cations.

Plutonium hexafluoride Chemical compound

Plutonium hexafluoride is the highest fluoride of plutonium, and is of interest for laser enrichment of plutonium, in particular for the production of pure plutonium-239 from irradiated uranium. This pure plutonium is needed to avoid premature ignition of low-mass nuclear weapon designs by neutrons produced by spontaneous fission of plutonium-240.

Tetrafluoroammonium

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 and the tetrafluoroborate BF−
4 anion.

Thionyl tetrafluoride Chemical compound

Thionyl tetrafluoride is an inorganic compound gas with the formula SOF4. It is also known as sulfur tetrafluoride oxide. The shape of the molecule is a distorted trigonal bipyramid, with the oxygen found on the equator. The atoms on the equator have shorter bond lengths than the fluorine atoms on the axis. The sulfur oxygen bond is 1.409Å. A S−F bond on the axis has length 1.596Å and the S−F bond on the equator has length 1.539Å. The angle between the equatorial fluorine atoms is 112.8°. The angle between axial fluorine and oxygen is 97.7°. The angle between oxygen and equatorial fluorine is 123.6° and between axial and equatorial fluorine is 85.7°. The fluorine atoms only produce one NMR line, probably because they exchange positions.

Sulfur chloride pentafluoride Chemical compound

Sulfur chloride pentafluoride is an inorganic compound with the formula SF
5Cl. It exists as a colorless gas at room temperature and is highly toxic, like most inorganic compounds containing the pentafluorosulfide (SF5) functional group. The compound adopts an octahedral geometry with C
4v symmetry. Sulfur chloride pentafluoride is the only commercially available reagent for adding the SF
5 group to organic compounds.

Vanadium pentafluoride Chemical compound

Vanadium(V) fluoride is the inorganic compound with the chemical formula VF5. It is a colorless volatile liquid. It is a highly reactive compound, as indicated by its ability to fluorinate organic substances.

Nitrogen pentafluoride (NF5) is a theoretical compound of nitrogen and fluorine that 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 NF+
4F−, which would be an ionic solid.

Chromium pentafluoride is the inorganic compound with the chemical formula CrF5. It is a red volatile solid that melts at 34 °C. It is the highest known chromium fluoride, since the hypothetical chromium hexafluoride has not yet been synthesized.

Nitrogen monofluoride Chemical compound

Nitrogen monofluoride (fluoroimidogen) is a metastable species that has been observed in laser studies. It is isoelectronic with O2. Like boron monofluoride, it has unusual higher than single-bonded fluorine. It is unstable with respect to its formal dimer, dinitrogen difluoride, as well as to its elements, nitrogen and fluorine. Nitrogen monofluoride can be formed by the decomposition of fluorine azide into N2F2 and N2. It is also produced when various radical species (H, O, N, CH3) react with nitrogen difluoride (NF2) to abstract one fluorine atom. Many of the reactions give the product in an excited state that has a characteristic chemiluminescence, and have thus been investigated for development as a chemical laser. The reactions are highly efficient and the product has a long lifetime. The reaction with molecular hydrogen (H2) involves a chain propagation via regeneration of the atomic hydrogen radical that can perpetuate for many cycles. An alternative azide process involves the reaction of atomic fluorine with hydrazoic acid to give an azide radical, which then reacts with another atomic fluorine to produce NF with N2 as a byproduct. This route avoids the necessity of using atomic hydrogen, a chemical that could otherwise cause the decomposition of NF.

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.

Fluorine azide Chemical compound

Fluorine azide or triazadienyl fluoride is a yellow green gas composed of nitrogen and fluorine with formula FN3. It is counted as an interhalogen compound, as the azide functional group is termed a pseudohalogen. It resembles ClN3, BrN3, and IN3 in this respect. The bond between the fluorine atom and the nitrogen is very weak, leading to this substance being very unstable and prone to explosion. Calculations show the F–N–N angle to be around 102° with a straight line of 3 nitrogen atoms.

Nitrogen difluoride Chemical compound

Nitrogen difluoride, also known as difluoroamino, is a reactive radical molecule with formula NF2. This small molecule is in equilibrium with its dimer dinitrogen tetrafluoride.

Difluorodisulfanedifluoride Chemical compound

1,1,1,2-tetrafluorodisulfane, also known as 1,2-difluorodisulfane 1,1-difluoride or just difluorodisulfanedifluoride (FSSF3) is an unstable molecular compound of fluorine and sulfur. The molecule has a pair of sulfur atoms, with one fluorine atom on one sulfur, and three fluorine atoms on the other. It has the uncommon property that all the bond lengths are different. The bond strength is not correlated with bond length but is inversely correlated with the force constant (Badger's rule). The molecule can be considered as sulfur tetrafluoride in which a sulfur atom is inserted into a S-F bond.

Pentafluorosulfur hypofluorite is an oxyfluoride of sulfur in the +6 oxidation state, with a fluorine atom attached to oxygen. The formula is SOF6. In standard conditions it is a gas.

Chlorine trifluoride oxide 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.

Diphosphorus tetrafluoride is a gaseous compound of phosphorus and fluorine with formula P2F4. Two fluorine atoms are connected to each phosphorus atom, and there is a bond between the two phosphorus atoms. Phosphorus can be considered to have oxidation state +2, as indicated by the name phosphorus difluoride.

References

  1. 1 2 Haase, J.; Oberhammer, H.; Zentrum, W. Zeil; Glemser, O.; Mews, R. (1 January 1971). "Die Molekülstraktur des Difluoramin-Schwefelpentafluorids SF5NF2" (PDF). Zeitschrift für Naturforschung A (in German). 26 (8): 1333. Bibcode:1971ZNatA..26.1333H. doi:10.1515/zna-1971-0813. S2CID   98859416.
  2. ↑ "Pentafluorosulfanyldifluoroamine". Pubchem. Retrieved 23 December 2015.
  3. 1 2 3 4 5 6 7 8 Logothetis, A. L.; Sausen, G. N.; Shozda, R. J. (February 1963). "The Preparation of Difluoroamino Sulfur Pentafluoride". Inorganic Chemistry. 2 (1): 173–175. doi:10.1021/ic50005a044.
  4. 1 2 Macintyre, Jane E. (23 July 1992). Dictionary of Inorganic Compounds. CRC Press. p. 3240. ISBN   9780412301209.
  5. 1 2 Lyman, John L.; Danen, Wayne C.; Nilsson, Alan C.; Nowak, Andrew V. (1979). "Multiple-photon excitation of difluoroamino sulfur pentafluoride: A study of absorption and dissociation". The Journal of Chemical Physics. 71 (3): 1206. Bibcode:1979JChPh..71.1206L. doi:10.1063/1.438466.
  6. ↑ Stump, Eugene C.; Padgett, Calvin D.; Brey, Wallace S. (17 November 1962). "The Synthesis of Difluoraminosulfur Pentafluoride". Inorganic Chemistry. 2 (3): 648–649. doi:10.1021/ic50007a062.
  7. ↑ Casanovas, Anne-Marie; Vial, Lawrence; Coll, Isabelle; Storer, Magali; Casanovas, Joseph; Clavreul, Regine (2012-12-06). "Decomposition of SF6 under AC and DC Corona Discharges in High-Pressure SF6 and SF6/N2 (10–90%) Mixtures". In Christophorou, Loucas G.; Olthoff, James K. (eds.). Gaseous Dielectrics VIII. Springer Science & Business Media. pp. 379–383. ISBN   9781461548997 . Retrieved 23 December 2015.
  8. ↑ Verma, R. D.; Kirchmeier, Robert L.; Shreeve, Jean'ne M. (1994-09-29). "Chemistry of Pentafluorosulfanyl Compounds". Advances in Inorganic Chemistry. Vol. 41. Academic Press. p. 144. ISBN   9780080578903.
  9. ↑ Christe, Karl O.; Wilson, William W.; Schack, Carl J.; Wilson, Richard D. (January 1985). "Lewis acid induced intramolecular redox reactions of difluoroamino compounds". Inorganic Chemistry. 24 (3): 303–307. doi:10.1021/ic00197a013.
  10. ↑ Dolbier Jr, W. R.; Knight, T. W.; Anghaie, S. (2002). "Development of Synthesis and Large Scale Technology for Ultrahigh Energy Density Fluoro-Organic Compounds" (PDF). DTIC. p. 2. Archived from the original on December 23, 2015. Retrieved 23 December 2015.
  11. ↑ O'Brien, Brian A.; DesMarteau, Darryl D. (September 1982). "Some reactions of fluoroimidotetrafluorosulfur". Journal of Fluorine Chemistry. 21 (1): 34. doi:10.1016/s0022-1139(00)85379-8.
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