Tetrasulfur tetranitride

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Tetrasulfur tetranitride
Tetrasulfur-tetranitride.png
Ball and stick model of tetrasulfur tetranitride Tetrasulfur-tetranitride-from-xtal-2000-3D-balls.png
Ball and stick model of tetrasulfur tetranitride
Space-filling model of tetrasulfur tetranitride Tetrasulfur-tetranitride-3D-vdW.png
Space-filling model of tetrasulfur tetranitride
Names
IUPAC name
Tetrasulfur tetranitride
Systematic IUPAC name
1,3,5,7-tetrathia-2,4,6,8-tetraazacyclooctan-2,4,6,8-tetrayl
Other names
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
UNII
  • InChI=1S/N4S4/c1-5-2-7-4-8-3-6-1 Yes check.svgY
    Key: LTPQFVPQTZSJGS-UHFFFAOYSA-N Yes check.svgY
  • N1=[S]N=[S]N=[S]N=[S]1
Properties
S4N4
Molar mass 184.287 g/mol
AppearanceVivid orange, opaque crystals
Melting point 187 °C (369 °F; 460 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Tetrasulfur tetranitride is an inorganic compound with the formula S 4 N 4. This vivid orange, opaque, crystalline explosive is the most important binary sulfur nitride, which are compounds that contain only the elements sulfur and nitrogen. It is a precursor to many S-N compounds and has attracted wide interest for its unusual structure and bonding. [1] [2]

Contents

Nitrogen and sulfur have similar electronegativities. When the properties of atoms are so highly similar, they often form extensive families of covalently bonded structures and compounds. Indeed, a large number of S-N and S-NH compounds are known with S4N4 as their parent.

Structure

S4N4 adopts an unusual "extreme cradle" structure, with D2d point group symmetry. It can be viewed as a derivative of a (hypothetical) eight-membered ring (or more simply a 'deformed' eight-membered ring) of alternating sulfur and nitrogen atoms. The pairs of sulfur atoms across the ring are separated by 2.586  Å, resulting in a cage-like structure as determined by single crystal X-ray diffraction. [3] The nature of the transannular S–S interactions remains a matter of investigation because it is significantly shorter than the sum of the van der Waals radii [4] but has been explained in the context of molecular orbital theory. [1] One pair of the transannular S atoms have valence 4, and the other pair of the transannular S atoms have valence 2.[ citation needed ] The bonding in S4N4 is considered to be delocalized, which is indicated by the fact that the bond distances between neighboring sulfur and nitrogen atoms are nearly identical. S4N4 has been shown to co-crystallize with benzene and the C60 molecule. [5]

Properties

S4N4 is stable to air. It is, however, unstable in the thermodynamic sense with a positive enthalpy of formation of +460 kJ/mol. This endothermic enthalpy of formation originates in the difference in energy of S4N4 compared to its highly stable decomposition products:

2 S4N4 → 4 N2 + S8

S4N4 is shock and friction sensitive and because one of its decomposition products is a gas, S4N4 is considered a primary explosive. [1] [6] Purer samples tend to be more sensitive. [7] Small samples can be detonated by striking with a hammer. S4N4 is thermochromic, changing from pale yellow below −30 °C to orange at room temperature to deep red above 100 °C. [1]

Synthesis

S4N4 was first prepared in 1835 by M. Gregory by the reaction of disulfur dichloride with ammonia, [8] a process that has been optimized: [9]

6 S2Cl2 + 16 NH3 → S4N4 + S8 + 12 [NH4]Cl

Coproducts of this reaction include heptasulfur imide (S7NH) and elemental sulfur, and the latter equilibrates with more S4N4 and ammonium sulfide: [10]

16 S + 16 NH3 ↔ S4N4 + 12 (NH4)S

A related synthesis employs [NH4]Cl instead: [1]

4 [NH4]Cl + 6 S2Cl2 → S4N4 + 16 HCl + S8

An alternative synthesis entails the use of (((CH3)3Si)2N)2S as a precursor with pre-formed S–N bonds. (((CH3)3Si)2N)2S is prepared by the reaction of lithium bis(trimethylsilyl)amide and SCl2.

2 ((CH3)3Si)2NLi + SCl2 → (((CH3)3Si)2N)2S + 2 LiCl

The (((CH3)3Si)2N)2S reacts with the combination of SCl2 and SO2Cl2 to form S4N4, trimethylsilyl chloride, and sulfur dioxide: [11]

2 (((CH3)3Si)2N)2S + 2 SCl2 + 2 SO2Cl2 → S4N4 + 8 (CH3)3SiCl + 2 SO2

Acid-base reactions

S4N4*BF3 S4N4.BF3-from-xtal-1967-3D-balls.png
S4N4·BF3

S4N4 is a Lewis base at nitrogen. It binds to strong Lewis acids, such as SbCl5 and SO3, or H[BF4]:

S4N4 + SbCl5 → S4N4·SbCl5
S4N4 + SO3 → S4N4·SO3
S4N4 + H[BF4] → [S4N4H]+[BF4]−

The cage is distorted in these adducts. [1]

S4N4 reacts with metal complexes, but the bonding situation may be quite complex. The cage remains intact in some cases but in other cases, it is degraded. [2] [12] For example, the soft Lewis acid CuCl forms a coordination polymer: [1]

n S4N4 + n CuCl → (S4N4)n-μ-(−Cu−Cl−)n

Reportedly, [Pt2Cl4(P(CH3)2 Ph)2] initially forms a complex with S4N4 at sulfur. This compound, upon standing, isomerizes to additionally bond through a nitrogen atom. S4N4 oxidatively adds to Vaska's complex ([Ir(Cl)(CO)(PPh 3)2] to form a hexacoordinate iridium complex where the S4N4 binds through two sulfur atoms and one nitrogen atom. [2]

Dilute NaOH hydrolyzes S4N4 as follows, yielding thiosulfate and trithionate: [1]

2 S4N4 + 6 OH− + 9 H2O → S2O2−3 + 2 S3O2−6 + 8 NH3

More concentrated base yields sulfite:

S4N4 + 6 OH− + 3 H2O → S2O2−3 + 2 SO2−3 + 4 NH3

As a precursor to other S-N compounds

Many S-N compounds are prepared from S4N4. [13]

In electrophilic substitution or 1,3-dipolar cycloaddition reactions, S4N4 behaves as a combination of the dithionitronium synthon and the sulfide synthon. Thus it adds to arenes and electron-rich alkynes to give 1,2,5‑ thiadiazoles. [14] Electron-poor alkynes attack S4N4 to give a different cycloadduct of stoichiometry RC(NS)2SCR′. [15] [14] With electron-rich alkenes, S4N4 behaves as a Diels-Alder diene. [14]

Passing gaseous S4N4 over silver metal yields the low temperature superconductor polythiazyl or polysulfurnitride (transition temperature (0.26±0.03) K [16] ), often simply called "(SN)x". In the conversion, the silver first becomes sulfided, and the resulting Ag2S catalyzes the conversion of the S4N4 into the four-membered ring S2N2, which readily polymerizes. [1]

S4N4 + 8 Ag → 4 Ag2S + 2 N2
x S4N4 → (SN)4x

Oxidation of S4N4 with elemental chlorine gives thiazyl chloride,[ citation needed ] but milder reagents give S4N+
3:

3 S4N4 + 2 S2Cl2 → 4 [S4N3]+Cl−
S4N4 + RC(=O)Cl → [S4N3]+Cl− + RNCO

That cation is relatively non-electrophilic and planar, with a delocalized π system. However, it adds triphenylphosphine to give [S(NPPh3)3]3+[Cl−]3, a triimide analogue to sulfur trioxide. Conversely, S4N+
3 salts react with aluminum azide to recover S4N4. [14]

Treatment with tetramethylammonium azide produces the similar 10-π heterocycle [S3N3]−:

8 S4N4 + 8 [(CH3)4N]+[N3]− → 8 [(CH3)4N]+[S3N3]− + S8 + 16 N2

In a related reaction, the use of the bis(triphenylphosphine)iminium azide gives a salt containing the blue [NS4]− anion: [13]

4 S4N4 + 2 [PPN]+[N3]− → 2 [PPN]+[NS4]− + S8 + 10 N2

[NS4]− has a chain structure approximated by the resonance [S=S=N−S−S−] ↔ [−S−S−N=S=S].

Reaction with piperidine generates [S4N5]−:

24 S4N4 + 32 C5H10NH → 8 [C5H10NH2]+[S4N5]− + 8 (C5H10N)2S + 3 S8 + 8 N2

A related cation is also known, i.e. [S4N5]+.

Triphenylphosphine abstracts a sulfur atom, replacing it with another triphenylphosphine moiety: [14]

S4N4 + 2 PPh3 → S3(PPh3)N4 + SPPh3

Safety

S4N4 is a categorized as a primary explosive that is shock and friction sensitive. While comparable to pentaerythritol tetranitrate (PETN) in terms of impact sensitivity, its friction sensitivity is equal to or even lower than lead azide. [17] Purer samples are more shock-sensitive than those contaminated with elemental sulfur. [9] [7]

Related Research Articles

<span class="mw-page-title-main">Nitrogen</span> Chemical element with atomic number 7 (N)

Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colourless and odourless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant chemical species in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth.

In chemistry, a nitride is a chemical compound of nitrogen. Nitrides can be inorganic or organic, ionic or covalent. The nitride anion, N3- ion, is very elusive but compounds of nitride are numerous, although rarely naturally occurring. Some nitrides have a found applications, such as wear-resistant coatings (e.g., titanium nitride, TiN), hard ceramic materials (e.g., silicon nitride, Si3N4), and semiconductors (e.g., gallium nitride, GaN). The development of GaN-based light emitting diodes was recognized by the 2014 Nobel Prize in Physics. Metal nitrido complexes are also common.

In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation state. The reverse of disproportionation, such as when a compound in an intermediate oxidation state is formed from precursors of lower and higher oxidation states, is called comproportionation, also known as symproportionation.

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

Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to PPh3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a ligand for transition metal complexes, including ones that serve as catalysts in organometallic chemistry. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether.

In inorganic chemistry, chlorosilanes are a group of reactive, chlorine-containing chemical compounds, related to silane and used in many chemical processes. Each such chemical has at least one silicon-chlorine bond. Trichlorosilane is produced on the largest scale. The parent chlorosilane is silicon tetrachloride.

<span class="mw-page-title-main">Phosphorus sulfides</span>

Phosphorus sulfides comprise a family of inorganic compounds containing only phosphorus and sulfur. These compounds have the formula P4Sn with n ≤ 10. Two are of commercial significance, phosphorus pentasulfide, which is made on a kiloton scale for the production of other organosulfur compounds, and phosphorus sesquisulfide, used in the production of "strike anywhere matches".

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

Sulfur dichloride is the chemical compound with the formula SCl2. This cherry-red liquid is the simplest sulfur chloride and one of the most common, and it is used as a precursor to organosulfur compounds. It is a highly corrosive and toxic substance, and it reacts on contact with water to form chlorine-containing acids.

Sulfur nitride may refer to a number of sulfur nitrogen compounds:

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

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

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

Disulfur dichloride is the inorganic compound of sulfur and chlorine with the formula S2Cl2. It is an amber oily liquid.

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

Polythiazyl, (SN)x, is an electrically conductive, gold- or bronze-colored polymer with metallic luster. It was the first conductive inorganic polymer discovered and was also found to be a superconductor at very low temperatures. It is a fibrous solid, described as "lustrous golden on the faces and dark blue-black", depending on the orientation of the sample. It is air stable and insoluble in all solvents.

Bis(trimethylsilyl)amine (also known as hexamethyldisilazane and HMDS) is an organosilicon compound with the molecular formula [(CH3)3Si]2NH. The molecule is a derivative of ammonia with trimethylsilyl groups in place of two hydrogen atoms. An electron diffraction study shows that silicon-nitrogen bond length (173.5 pm) and Si-N-Si bond angle (125.5°) to be similar to disilazane (in which methyl groups are replaced by hydrogen atoms) suggesting that steric factors are not a factor in regulating angles in this case. This colorless liquid is a reagent and a precursor to bases that are popular in organic synthesis and organometallic chemistry. Additionally, HMDS is also increasingly used as molecular precursor in chemical vapor deposition techniques to deposit silicon carbonitride thin films or coatings.

<span class="mw-page-title-main">Bis(trimethylsilyl)sulfide</span> Chemical compound

Bis(trimethylsilyl) sulfide is the chemical compound with the formula ((CH3)3Si)2S. Often abbreviated (tms)2S, this colourless, vile-smelling liquid is a useful aprotic source of "S2−" in chemical synthesis.

<span class="mw-page-title-main">Bis(triphenylphosphine)iminium chloride</span> Chemical compound

Bis(triphenylphosphine)iminium chloride is the chemical compound with the formula [( 3P)2N]Cl, often abbreviated [(Ph3P)2N]Cl, where Ph is phenyl C6H5, or even abbreviated [PPN]Cl or [PNP]Cl or PPNCl or PNPCl, where PPN or PNP stands for (Ph3P)2N. This colorless salt is a source of the [(Ph3P)2N]+ cation, which is used as an unreactive and weakly coordinating cation to isolate reactive anions. [(Ph3P)2N]+ is a phosphazene.

<span class="mw-page-title-main">Lithium bis(trimethylsilyl)amide</span> Chemical compound

Lithium bis(trimethylsilyl)amide is a lithiated organosilicon compound with the formula LiN(Si(CH3)3)2. It is commonly abbreviated as LiHMDS or Li(HMDS) (lithium hexamethyldisilazide - a reference to its conjugate acid HMDS) and is primarily used as a strong non-nucleophilic base and as a ligand. Like many lithium reagents, it has a tendency to aggregate and will form a cyclic trimer in the absence of coordinating species.

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

Thiazyl fluoride, NSF, is a colourless, 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.

<span class="mw-page-title-main">Metal bis(trimethylsilyl)amides</span>

Metal bis(trimethylsilyl)amides are coordination complexes composed of a cationic metal M with anionic bis(trimethylsilyl)amide ligands (the −N 2 monovalent anion, or −N 2 monovalent group, and are part of a broader category of metal amides.

<span class="mw-page-title-main">Tris(trimethylsilyl)amine</span> Chemical compound

Tris(trimethylsilyl)amine is the simplest tris(trialkylsilyl)amine which are having the general formula (R3Si)3N, in which all three hydrogen atoms of the ammonia are replaced by trimethylsilyl groups (-Si(CH3)3). Tris(trimethylsilyl)amine has been for years in the center of scientific interest as a stable intermediate in chemical nitrogen fixation (i. e. the conversion of atmospheric nitrogen N2 into organic substrates under normal conditions).

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

Trithiazyl trichloride is the inorganic compound with the formula (NSCl)3. A white solid, it is a precursor to other sulfur nitrides, but has no commercial applications.

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

Tetraselenium tetranitride is the inorganic compound with the formula Se4N4. Like the analogous tetrasulfur tetranitride S4N4, Se4N4 is an orange solid. It is however less soluble and more shock-sensitive than S4N4.

References

  1. 1 2 3 4 5 6 7 8 9 Greenwood, N. N.; Earnshaw, A. (1997). Chemical Elements (2nd ed.). Boston, MA: Butterworth-Heinemann. pp. 721–725.
  2. 1 2 3 Chivers, T. (2004). A Guide To Chalcogen-Nitrogen Chemistry. Singapore: World Scientific Publishing. ISBN   981-256-095-5.
  3. ↑ Sharma, B. D.; Donohue, J. (1963). "The Crystal and Molecular Structure of Sulfur Nitride, S4N4". Acta Crystallographica . 16 (9): 891–897. Bibcode:1963AcCry..16..891S. doi:10.1107/S0365110X63002401.
  4. ↑ Rzepa, H. S.; Woollins, J. D. (1990). "A PM3 SCF-MO Study of the Structure and Bonding in the Cage Systems S4N4 and S4N4X (X = N+, N−, S, N2S, P+, C, Si, B− and Al−)". Polyhedron . 9 (1): 107–111. doi:10.1016/S0277-5387(00)84253-9.
  5. ↑ Konarev, D. V.; Lyubovskaya, R. N.; Drichko, N. V.; et al. (2000). "Donor-Acceptor Complexes of Fullerene C60 with Organic and Organometallic Donors". Journal of Materials Chemistry . 10 (4): 803–818. doi:10.1039/a907106g.
  6. ↑ Assessment, US EPA National Center for Environmental (2009-03-15). "Analysis of the Explosive Properties of Tetrasulfur Tetranitride, S4N4". hero.epa.gov. Retrieved 2024-05-24.
  7. 1 2 Ebrahimian, G. Reza; Fuchs, Philip L. (2009-03-15), "Tetrasulfur Tetranitride", in John Wiley & Sons, Ltd (ed.), Encyclopedia of Reagents for Organic Synthesis, Chichester, UK: John Wiley & Sons, Ltd, doi:10.1002/047084289x.rn00933, ISBN   978-0-471-93623-7 , retrieved 2024-05-24
  8. ↑ Jolly, W. L.; Lipp, S. A. (1971). "Reaction of Tetrasulfur Tetranitride with Sulfuric Acid". Inorganic Chemistry. 10 (1): 33–38. doi:10.1021/ic50095a008.
  9. 1 2 Villena-Blanco, M.; Jolly, W. L.; et al. (1967). "Tetrasulfur Tetranitride, S4N4". In S. Y. Tyree Jr (ed.). Inorganic Syntheses. Inorganic Syntheses. Vol. 9. pp. 98–102. doi:10.1002/9780470132401.ch26. ISBN   978-0-470-13168-8.
  10. ↑ Audrieth, Ludwig F.; Kleinberg, Jacob (1953). Non-aqueous solvents. New York: John Wiley & Sons. p. 44. LCCN   52-12057.
  11. ↑ Maaninen, A.; Shvari, J.; Laitinen, R. S.; Chivers, T (2002). "Compounds of General Interest". In Coucouvanis, Dimitri (ed.). Inorganic Syntheses. Inorganic Syntheses. Vol. 33. pp. 196–199. doi:10.1002/0471224502.ch4. ISBN   9780471208259.
  12. ↑ Kelly, P. F.; Slawin, A. M. Z.; Williams, D. J.; Woollins, J. D. (1992). "Caged explosives: Metal-Stabilized Chalcogen Nitrides". Chemical Society Reviews . 21 (4): 245–252. doi:10.1039/CS9922100245.
  13. 1 2 Bojes, J.; Chivers, T.; Oakley, R. D.; et al. (1989). "Binary Cyclic Nitrogen-Sulfur Anions". In Allcock, H. R. (ed.). Inorganic Syntheses. Inorganic Syntheses. Vol. 25. pp. 30–35. doi:10.1002/9780470132562.ch7. ISBN   9780470132562.
  14. 1 2 3 4 5 Roesky, H. W. (1971). "The Sulfur–Nitrogen Bond". In Senning, Alexander (ed.). Sulfur in Organic and Inorganic Chemistry. Vol. 1. New York: Marcel Dekker. pp. 14–18. ISBN   0-8247-1615-9. LCCN   70-154612.
  15. ↑ Dunn, P. J.; Rzepa, H. S. (1987). "The Reaction Between Tetrasulphur Tetranitride (S4N4) and Electron-deficient Alkynes. A Molecular Orbital Study". Journal of the Chemical Society, Perkin Transactions 2 . 1987 (11): 1669–1670. doi:10.1039/p29870001669.
  16. ↑ Greene, R. L.; Street, G. B.; Suter, L. J. (1975). "Superconductivity in Polysulfur Nitride (SN)x". Physical Review Letters . 34 (10): 577–579. Bibcode:1975PhRvL..34..577G. doi:10.1103/PhysRevLett.34.577.
  17. ↑ Assessment, US EPA National Center for Environmental (2009-03-15). "Analysis of the Explosive Properties of Tetrasulfur Tetranitride, S4N4". hero.epa.gov. Retrieved 2024-05-24.
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