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User:Villarde/Thiazyl fluoride

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Thiazyl fluoride
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/FNS/c1-3-2 checkY
    Key: IMFUYZDKLVTPSW-UHFFFAOYSA-N checkY
  • InChI=1/FNS/c1-3-2
    Key: IMFUYZDKLVTPSW-UHFFFAOYAG
  • FS#N
Properties
NSF
Molar mass 65.07 g mol−1
Appearance colourless gas
Melting point −89 °C (−128 °F; 184 K)
Boiling point 0.4 °C (32.7 °F; 273.5 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
2D contour plot of the electron density using the Laplacian function of thiazyl fluoride.

Thiazyl fluoride, NSF, is a colorless, pungent gas at room temperature and condenses to a pale yellow liquid at 0.4 °C. Along with thiazyl trifluoride, NSF3, it is an important precursor to sulfur–nitrogen–fluorine compounds. It is notable for its extreme hygroscopicity.

Synthesis edit

Thiazyl fluoride can be synthesized by various methods, such as fluorination of tetrasulfur tetranitride,  , with silver(II) fluoride or mercuric fluoride in tetrachloromethane, and purified by vacuum distillation.[1][2] However, because this synthetic pathway yields numerous side-products, an alternative approach is the reaction of imino(triphenyl)phosphines with sulfur tetrafluoride by cleavage of the   bond to form sulfur difluoride imides and triphenyldifluorophosphorane.[3] These products readily decompose yielding thiazyl fluoride.

For synthesis on a preparative scale, the decomposition of compounds already containing the   moiety is commonly used:

 

Reactivity edit

Thiazyl fluoride reacts violently with water, decomposes at room temperature, and should be stored at −78 °C.[4]

Reactions with Electrophiles edit

The site of electrophilic attack is primarily dependent upon the strength of the electrophile. For example, hard Lewis acids attack at the site of fluorine to afford thiazyl salts:

 

Reacting strong Lewis acids, such as AsF5 and SbF5, can cleave NSF to yield the thiazyl cation and a fluoride ion.[5]

By contrast, transition metal cations (which are classified as medium-hard acids) attack at the nitrogen atom due in part to Coulombic interactions. Soft acids with low valencies may attack at the sulfur atom. In the scheme below, electrophilic attack by a transition metal cation to NSF readily releases sulfur dioxide due to weak σ bonding and minimal π-back bonding at the sulfur atom.[6]

 

Thiazyl fluoride may be stabilized as a complexing ligand to cationic carbonyl-metal compounds, such as  .[6]

Reactions with Nucleophiles edit

Nucleophilic attack on thiazyl fluoride occurs at the sulfur atom, whereby either the coordination number of sulfur is increased, or a fluorine atom is substituted.[7]

Nucleophilic Substitution edit

The triple bond in NSF is retained during nucleophilic substitution, and trimerizes at room temperature.

 

The N≡S ON(CF3)2 compound can be stabilized by incorporation of a carbonyl-metal complex.[6]

Nucleophilic Addition edit

Nucleophilic attack occurs at the site of the sulfur atom, thereby increasing its coordination number. Reacting cesium fluoride and NSF affords the salt given below.

 

The halogen derivatives XNSF2 (X = F, Cl, Br, I) can be synthesized from reacting Hg(NSF)2 with X2; whereby, ClNSF2 is the most stable compound observed in this series.[8]

Oligermization and Cycloaddition edit

The length of the   bond (1.448 Å) is short, indicating multiple bonding, and can be represented by the following resonance structures:

 

At room temperature, thiazyl fluoride undergoes cyclic trimerization via the   multiple bonding:

 

1,3,5-trifluoro-1 ,3 ,5 ,2,4,6-trithiatriazine is the yielded cyclic trimer, where each sulfur atom remains tetravalent.

Thiazyl fluoride also reacts via exothermic cycloaddition in the presence of dienes.

 

Properties edit

Structure and Bonding edit

 
Frontier molecular orbitals of thiazyl fluoride calculated at the r2SCAN-3c level of theory

The NSF molecule has 18 total valence electrons and is isoelectronic to sulfur dioxide,  . Thiazyl fluoride adopts Cs-symmetry and has been shown by isotopic substitution to be bent in the ground state.[9][10] A combination of rotational analysis with Franck-Condon calculations has been applied to study the electronic excitation from the A'' A' states, which results in the elongation of the   bond by 0.11 Å and a decrease in the  NSF by 15.3 .[11]

In X-ray structural analysis of the cations  ( ), each NSF molecule is bound to the metal center through nitrogen.[6] The observed bond lengths from   to   are shortened which is related to the contraction of ionic radii as you move across the period.

References edit

  1. ^ Fischer, Gad (1974-05-01). "Vibrational assignments in the electronic spectra of thiazyl fluoride". Journal of Molecular Spectroscopy. 51 (2): 208–215. doi:10.1016/0022-2852(74)90050-2. ISSN 0022-2852.
  2. ^ Glemser, Oskar; Schröder, Hans; Haeseler, Harke (1955-01-01). "Über Schwefel-Stickstoff-Fluorverbindungen". Naturwissenschaften (in German). 42 (2): 44–44. doi:10.1007/BF00621536. ISSN 1432-1904.
  3. ^ Appel, Rolf; Laßmann, Eberhard (1971-07). "Über eine neue Synthese des Thiazylfluorids, NSF". Chemische Berichte. 104 (7): 2246–2249. doi:10.1002/cber.19711040727. ISSN 0009-2940. {{cite journal}}: Check date values in: |date= (help)
  4. ^ Mews, Rudiger; Keller, Klaus; Glemser, Oskar; Seppelt, K.; Thrasher, J. (2007-01-05), Shreeve, Jean'ne M. (ed.), "Acyclic Sulfur Nitrogen Fluorine Compounds", Inorganic Syntheses, Hoboken, NJ, USA: John Wiley & Sons, Inc., pp. 12–17, doi:10.1002/9780470132555.ch6, ISBN 978-0-470-13255-5, retrieved 2022-12-09
  5. ^ Mews, Rüdiger (1976-11). "Das Thionitrosylkation NS+ als Synthesereagens". Angewandte Chemie (in German). 88 (22): 757–758. doi:10.1002/ange.19760882205. {{cite journal}}: Check date values in: |date= (help)
  6. ^ a b c d Oskar Glemser and Rüdiger Mews (1980). "Chemistry of Thiazyl Fluoride (NSF) and Thiazyl Trifluoride (NSF3): A Quarter Century of Sulfur-Nitrogen-Fluorine Chemistry". Angew. Chem. Int. Ed. Engl. 19 (11): 883–899. doi:10.1002/anie.198008831.
  7. ^ Cohen, B.; Hooper, T. R.; Hugill, D.; Peacock, R. D. (1965-08). "Preparation of Thiazyl Fluorides". Nature. 207 (4998): 748–749. doi:10.1038/207748b0. ISSN 1476-4687. {{cite journal}}: Check date values in: |date= (help)
  8. ^ Glemser, Oskar; Mews, Rüdiger; Roesky, Herbert W. (1969-05). "Darstellung und Eigenschaften von Quecksilber‐bis‐schwefeldifluoridimid, N ‐Chlor‐schwefeldifluoridimid und N ‐Brom‐schwefeldifluoridimid". Chemische Berichte. 102 (5): 1523–1528. doi:10.1002/cber.19691020513. ISSN 0009-2940. {{cite journal}}: Check date values in: |date= (help)
  9. ^ So, Suk Ping; Richards, W. Graham (1978-01-01). "Geometries and stabilities of NSF and SNF". Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics. 74 (0): 1743–1745. doi:10.1039/F29787401743. ISSN 0300-9238.
  10. ^ Dixon, R. N.; Duxbury, G.; Fleming, G. R.; Hugo, J. M. V. (1972-05-01). "The photoelectron spectrum of thiazyl fluoride". Chemical Physics Letters. 14 (1): 60–63. doi:10.1016/0009-2614(72)87141-0. ISSN 0009-2614.
  11. ^ Barrow, T.; Dixon, R.N. (1973-07). "The rotational analysis of a 1 A ″- 1 A ′ band system of thiazyl fluoride". Molecular Physics. 26 (1): 109–117. doi:10.1080/00268977300101421. ISSN 0026-8976. {{cite journal}}: Check date values in: |date= (help)
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