Tetrasulfur tetranitride 2582573 225754334 2008-07-15T06:47:35Z DOI bot 6652755 Citation maintenance. Formatted: title, volume, pages, doi. Initiated by [[User:Rifleman_82|Rifleman_82]]. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Chembox new | Name = Tetrasulfur tetranitride | ImageFile = Tetrasulfur-tetranitride.png <!-- | ImageSize = 150px --> | ImageName = The structure of tetrasulfur tetranitride | ImageFile1 = Tetrasulfur-tetranitride-3D-vdW.png <!-- | ImageSize1 = 120px --> | ImageName1 = The structure of tetrasulfur tetranitride | IUPACName = tetrasulfur tetranitride | Section1 = {{Chembox Identifiers | CASNo = 28950-34-7 }} | Section2 = {{Chembox Properties | Formula = S<sub>4</sub>N<sub>4</sub> | MolarMass = 184.29&nbsp;g/mol | Appearance = Orange solid | Solubility = Insoluble | Solvent = other solvents | SolubleOther = [[Carbon disulfide|CS<sub>2</sub>]], [[benzene]] | MeltingPt = 187 °C (460 K)}} }} '''Tetrasulfur tetranitride''' is an [[inorganic compound]] with the [[chemical formula|formula]] S<sub>4</sub>N<sub>4</sub>. This gold-poppy coloured solid is the most important binary sulfur nitride, which are compounds that contain only the [[chemical element|elements]] [[sulfur]] and [[nitrogen]]. It is a precursor to many S-N compounds and has attracted wide interest for its unusual structure and bonding.<ref name="Greenwood">Greenwood, N. N.; Earnshaw, A. ''Chemical Elements''; 2nd edition; Butterworth-Heinemann: Boston, MA, 1997, pp 721-725.</ref><ref name=Chivers>Chivers, T. “A Guide To Chalcogen-Nitrogen Chemistry” World Scientific Publishing Company: Singapore; 2004. ISBN 981-256-095-5</ref> Nitrogen and sulfur have similar [[electronegativity|electronegativities]], which is the ability to attract electrons. When atoms are so evenly matched, they often form extensive families of [[covalent]]ly bonded structures. Indeed, a large number of S-N and S-NH compounds are known with S<sub>4</sub>N<sub>4</sub> as their parent. ==Structure== S<sub>4</sub>N<sub>4</sub> adopts an unusual “extreme cradle” structure, with D<sub>2d</sub> [[symmetry group|point group symmetry]]. It can be viewed as a derivative of a hypothetical 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.<ref>{{cite journal | author = Brahama D. Sharma and Jerry Donohue | title = The crystal and molecular structure of sulfur nitride, S<sub>4</sub>N<sub>4</sub> | journal = [[Acta Crystallographica]] | year = 1963 | volume = 16 | pages = 891–897 | doi = 10.1107/S0365110X63002401}}</ref> 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 Waal's distances.<ref>{{cite journal | title = A PM3 SCF-MO Study of the Structure and Bonding in the Cage Systems S<sub>4</sub>N<sub>4</sub> and S<sub>4</sub>N<sub>4</sub>X (X=N [+], N[-], S, N<sub>2</sub>S, P[+], C, Si, B[-] and Al[-]) | author = [[Henry Rzepa|H. S. Rzepa]] and J. D. Woollins | journal = [[Polyhedron (journal)|Polyhedron]] | year = 1990 | volume = 9 | pages = 107 | doi = 10.1016/S0277-5387(00)84253-9}}</ref> but has been explained in the context of [[molecular orbital theory]].<ref name="Greenwood" /> The bonding in S<sub>4</sub>N<sub>4</sub> is considered to be delocalized, which is indicated by the fact that the bond distances between neighboring sulfur and nitrogen atoms are almost the same. ==Properties== S<sub>4</sub>N<sub>4</sub> is stable to [[air]]. It is, however, unstable in the [[thermodynamic]] sense with a positive [[heat of formation]] of +460 kJ&nbsp;mol<sub>−1</sub>). This [[endothermic]] heat of formation anticipates its inherent instability, and originates in the difference in energy of S<sub>4</sub>N<sub>4</sub> compared to its highly stable decomposition products: ::S<sub>4</sub>N<sub>4</sub> → 2 N<sub>2</sub> + ½ S<sub>8</sub> It is not really very unusual for complex molecules to be unstable in a thermodynamic sense yet stable kinetically; this situation describes many compounds. This combination of kinetic stability and thermodynamic instability is, however, uncommon for very simple compositions, such as sulfur nitride. Because one of its decomposition products is a gas, S<sub>4</sub>N<sub>4</sub> is an explosive.<ref name="Greenwood" /> Purer samples tend to be more explosive. Small samples can be detonated by striking with a hammer. S<sub>4</sub>N<sub>4</sub> is [[thermochromic]], changing from pale yellow below −30 °C to orange at room temperature to deep red above 100 °C.<ref name="Greenwood" /> ==Synthesis== <!-- was first prepared in 1835 by W. Gregory - how?--> Until recently, S<sub>4</sub>N<sub>4</sub> was prepared by the reaction of [[ammonia]] with [[sulfur dichloride|SCl<sub>2</sub>]] in [[carbon tetrachloride]] followed by extraction into [[dioxane]].<ref name="Blanco">{{cite journal | author = Villena-Blanco, M.;Jolly, W.L.; Tyree | journal = [[Inorg. Synth.]] |year = 1967 | volume = 9 | pages = 98–102 | doi = 10.1002/9780470132401.ch26 | title = Tetrasulfur Tetranitride, S4N4}}</ref> ::6 SCl<sub>2</sub> + 16 NH<sub>3</sub> → S<sub>4</sub>N<sub>4</sub> + S<sub>8</sub> + 12 [[Ammonium chloride|NH<sub>4</sub>Cl]] A related synthesis employs [[ammonium chloride|NH<sub>4</sub>Cl]] in place of ammonia:<ref name="Greenwood" /> ::4 NH<sub>4</sub>Cl + 6 [[Sulfur monochloride|S<sub>2</sub>Cl<sub>2</sub>]] → S<sub>4</sub>N<sub>4</sub> + 16 HCl + S<sub>8</sub> A more recent synthesis entails the use of {[Me<sub>3</sub>Si)<sub>2</sub>N]<sub>2</sub>S} as a precursor with pre-formed S-N bonds. {[Me<sub>3</sub>Si)<sub>2</sub>N]<sub>2</sub>S} is prepared by the reaction of [[lithium bis(trimethylsilyl)amide]] and [[sulfur dichloride|SCl<sub>2</sub>]]. ::2 [(CH<sub>3</sub>)<sub>3</sub>Si]<sub>2</sub>NLi + SCl<sub>2</sub> → [(CH<sub>3</sub>)<sub>3</sub>Si)<sub>2</sub>N]<sub>2</sub>S + 2 LiCl The {[(CH<sub>3</sub>)<sub>3</sub>Si)<sub>2</sub>N]<sub>2</sub>S} reacts with the combination of SCl<sub>2</sub> and [[sulfuryl chloride|SO<sub>2</sub>Cl<sub>2</sub>]] to form S<sub>4</sub>N<sub>4</sub>.<ref>{{cite journal | author = Maaninen, A.; Shvari, J.; Laitinen, R.S.; Chivers, T; | journal = [[Inorg. Synth.]] | year = 2002 | volume = 33 | pages = 196–199}}</ref> ::[(CH<sub>3</sub>)<sub>3</sub>Si)<sub>2</sub>N]<sub>2</sub>S + SCl<sub>2</sub> + [[thionyl chloride|SO<sub>2</sub>Cl<sub>2</sub>]] → S<sub>4</sub>N<sub>4</sub> + 4 [[Trimethylsilyl chloride|(CH<sub>3</sub>)<sub>3</sub>SiCl]] + [[Sulfur dioxide|SO<sub>2</sub>]] ==Acid-base reactions== S<sub>4</sub>N<sub>4</sub> serves as a [[Lewis base]] by binding through nitrogen to strongly [[Lewis acid]]ic compounds such as [[Antimony pentachloride|SbCl<sub>5</sub>]] and [[Sulfur trioxide|SO<sub>3</sub>]]. The cage is distorted in these adducts, thus delocolization of [[electron]]s may be disrupted.<ref name="Greenwood" /> :S<sub>4</sub>N<sub>4</sub> + SbCl<sub>5</sub> → S<sub>4</sub>N<sub>4</sub><sup>.</sup>SbCl<sub>5</sub> :S<sub>4</sub>N<sub>4</sub> + SO<sub>3</sub> → S<sub>4</sub>N<sub>4</sub><sup>.</sup>SO<sub>3</sub> The reaction of [Pt<sub>2</sub>Cl<sub>4</sub>(PMe<sub>2</sub>Ph)<sub>2</sub>] with S<sub>4</sub>N<sub>4</sub> is reported to form a complex where a sulfur forms a dative bond to the metal, this compound upon standing is isomerised to a complex in which a nitrogen atom forms the additional bond to the metal centre. It is protonated by HBF<sub>4</sub>: :S<sub>4</sub>N<sub>4</sub> + HBF<sub>4</sub> → [S<sub>4</sub>N<sub>4</sub>H<sup>+</sup>]<nowiki>[</nowiki>[[tetrafluoroborate|BF<sub>4</sub>]]<sup>−</sup>] The soft Lewis acid [[copper(I) chloride|CuCl]] forms a polymer containing intact S<sub>4</sub>N<sub>4</sub> rings as the bridging [[ligands]]:<ref name="Greenwood" /> ::nS<sub>4</sub>N<sub>4</sub> + nCuCl → (S<sub>4</sub>N<sub>4</sub>)<sub>n</sub>-μ-(-Cu-Cl-)<sub>n</sub> S<sub>4</sub>N<sub>4</sub> is sensitive to [[hydrolysis]] in the presence of [[base (chemistry)|base]]. Dilute [[sodium hydroxide|NaOH]] hydrolyzes S<sub>4</sub>N<sub>4</sub> as follows:<ref name="Greenwood" /> :2S<sub>4</sub>N<sub>4</sub> + 6 OH<sup>−</sup> + 9 H<sub>2</sub>O → [[thiosulfate|S<sub>2</sub>O<sub>3</sub><sup>2−</sup>]] + 2 S<sub>3</sub>O<sub>6</sub><sup>2−</sup> + 8 NH<sub>3</sub> Whereas more concentrated [[base (chemistry)|base]] yields [[sulfite]]: :S<sub>4</sub>N<sub>4</sub> + 6 OH<sup>−</sup> + 3 H<sub>2</sub>O → S<sub>2</sub>O<sub>3</sub><sup>2−</sup> + 2 SO<sub>3</sub><sup>2−</sup> + 4 NH<sub>3</sub> ==Reactions with metal complexes== This area has been reviewed.<ref>{{cite journal | author = Paul. F. Kelly, Alexandra. M.Z. Slawin, David J. Williams and J. Derek Woollins | journal = [[Chemical Society Reviews]] | year = 1992 | pages = 245 | doi = 10.1039/CS9922100245 | title = Caged explosives: metal-stabilized chalcogen nitrides | volume = 21}}</ref><ref name=Chivers/> ===Reactions of S<sub>4</sub>N<sub>4</sub> where the ring remains intact=== S<sub>4</sub>N<sub>4</sub> reacts with [[Vaska's complex]] ([Ir(Cl)(CO)(PPh<sub>3</sub>)<sub>2</sub>] in an [[oxidative addition]] reaction to form a six coordinate [[iridium]] complex where the S<sub>4</sub>N<sub>4</sub> binds through two sulfur atoms and one nitrogen atom. This compound arises by the formal breaking of one S-N bond in the oxidative addition, followed by the coordination of the lone pair on another sulfur atom to form a [[dative bond]]. A related Pt(IV) compound arises from [[Zeise's salt]]. ===Reactions of S<sub>4</sub>N<sub>4</sub> where the ring does not remain intact=== The reaction of S<sub>4</sub>N<sub>4</sub> with the [Pd<sub>2</sub>Cl<sub>6</sub>]<sup>2−</sup> anion forms a series of three palladium complexes in which the S<sub>4</sub>N<sub>4</sub> ring has been fragmented. ==S<sub>4</sub>N<sub>4</sub> as a precursor to other S-N compounds== Many important S-N compounds are prepared from S<sub>4</sub>N<sub>4</sub>.<ref>{{cite journal | author = Bojes, J.; Chivers, T; Oakley, R. D. | title = Binary Cyclic Nitrogen-Sulfur Anions | journal = [[Inorg. Synth.]] | year = 1989 | volume = 25 | pages = 30–40 | doi = 10.1002/9780470132562.ch7}}</ref> Reaction with [[piperidine]] generates [S<sub>4</sub>N<sub>5</sub>]<sup>−</sup>: :3 S<sub>4</sub>N<sub>4</sub> + 4 C<sub>5</sub>H<sub>10</sub>NH → (C<sub>5</sub>H<sub>10</sub>NH<sub>2</sub>)<sup>+</sup>[S<sub>4</sub>N<sub>5</sub>]<sup>−</sup> + (C<sub>5</sub>H<sub>10</sub>N)<sub>2</sub>S + ⅜ S<sub>8</sub> + N<sub>2</sub> It is indicative of the richness of this area that a related [[cation]] is also known, i.e. [S<sub>4</sub>N<sub>5</sub>]<sup>+</sup>. Treatment with [[Quaternary ammonium cation|tetramethylammonium]] [[azide]] produces the heterocycle [S<sub>3</sub>N<sub>3</sub>]<sup>−</sup>: ::S<sub>4</sub>N<sub>4</sub> + 4 NMe<sub>4</sub>N<sub>3</sub> → NMe<sub>4</sub>[S<sub>3</sub>N<sub>3</sub>] + ⅛ S<sub>8</sub> + 2 N<sub>2</sub> In the language of [[Pi bond|electron counting]], [S<sub>3</sub>N<sub>3</sub>]<sup>−</sup> has 10 pi-electrons: 2e<sup>−</sup>/S plus 1e<sup>−</sup>/N plus 1e<sup>−</sup> for the negative charge. In an apparently related reaction, the use of [[bis(triphenylphosphine)iminium chloride|PPN]]<sup>+</sup>N<sub>3</sub> gives the blue '''perthionitrite salt''': ::2 S<sub>4</sub>N<sub>4</sub> + PPN(N<sub>3</sub>) → PPN[NS<sub>3</sub>] + ½ S<sub>8</sub> + 5 N<sub>2</sub> The anion NS<sub>3</sub><sup>−</sup> is a chain described often as S=N-S-S<sup>−</sup>. ==Reaction with acetylenes== S<sub>4</sub>N<sub>4</sub> reacts with electron poor [[alkyne|acetylenes]].<ref>{{cite journal | title = The Reaction between Tetrasulphur Tetranitride (S4N4) and Electron-deficient Alkynes. A Molecular Orbital Study | author = P. J. Dunn and [[Henry Rzepa|H. S. Rzepa]] | journal = Journal of the Chemical Society, Perkin Transactions 2 | year = 1987 | pages = 1669–1670 | doi = 10.1039/p29870001669}}</ref> =="SN<sub>x</sub>"== Passing gaseous S<sub>4</sub>N<sub>4</sub> over [[silver]] metal yields the low temperature [[superconductor]] [[polythiazyl]] or polysulfurnitride (transition temperature (0.26±0.03)&nbsp;K<ref name="Greene">R. L. Greene, G. B. Street and L. J. Suter, Superconductivity in Polysulfur Nitride (SN)<sub>x</sub>, ''Phys. Rev. Lett.'' '''34''', 577–579 (1975) {{doi|10.1103/PhysRevLett.34.577}}</ref>), often simply called "(SN)<sub>x</sub>." In the conversion, the [[silver]] first becomes sulfided, and the resulting Ag<sub>2</sub>S catalyzes the conversion of the S<sub>4</sub>N<sub>4</sub> into the four-membered ring S<sub>2</sub>N<sub>2</sub>, which readily [[polymer]]izes.<ref name="Greenwood" /> :S<sub>4</sub>N<sub>4</sub> + 8 Ag → 4 [[silver sulfide|Ag<sub>2</sub>S]] + 2 N<sub>2</sub> :S<sub>4</sub>N<sub>4</sub> → (SN)<sub>x</sub> ==Miscellaneous facts== S<sub>4</sub>N<sub>4</sub> has been shown to co-crystallize with [[benzene]] and the [[fullerene|C<sub>60</sub>]] molecule.<ref name="Konarev">{{cite journal | author = Konarev, D.V. et al. | title = Donor-acceptor Complexes of Fullerene C<sub>60</sub> with Organic and Organometallic Donors | journal = [[Journal of Materials Chemistry]] | year = 2000 | volume = 10 | pages = 803–818 | doi = 10.1039/a907106g}}</ref> ==Se<sub>4</sub>N<sub>4</sub>== The [[selenium]] compound Se<sub>4</sub>N<sub>4</sub> is known and has been the subject of some research.<ref>{{cite journal | author = Kelly, P.F. and Woollins, J.D., | title = The Reactivity of Se<sub>4</sub>N<sub>4</sub> in Liquid Ammonia | journal = [[Polyhedron (journal)|Polyhedron]] | year = 1993 | volume = 12 | pages = 1129–1133 | doi = 10.1016/S0277-5387(00)88201-7}}</ref><ref>{{cite journal | author = Kelly, P.F., Slawin, A.M.Z. and Soriano-Rama, A. | title = Use of Se<sub>4</sub>N<sub>4</sub> and Se(NSO)<sub>2</sub> in the preparation of palladium adducts of diselenium dinitride, Se<sub>2</sub>N<sub>2</sub>; crystal structure of [PPh4]2[Pd2Br6(Se2N2) | journal = [[Dalton Transactions]] | year = 1997 | pages = 559–562 | doi = 10.1039/a606311j }}</ref> In addition, adducts of [[aluminium chloride]] with Se<sub>2</sub>N<sub>2</sub> have been isolated, this is formed from Se<sub>4</sub>N<sub>4</sub>.<ref>{{cite journal | author = Kelly, P.F. and Slawin, A.M.Z. | title = Preparation and crystal structure of [(AlBr3)2(Se2N2)], the first example of a main-group element adduct of diselenium dinitride | journal = [[Dalton Transactions]] | year = 1996 | pages = 4029–4030 | doi = 10.1039/DT9960004029}}</ref> ==Safety== S<sub>4</sub>N<sub>4</sub> is shock-sensitive, thus grinding solid samples should be avoided. Purer samples are reportedly more sensitive than those contaminated with elemental sulfur. ==References== {{reflist}} [[Category:Explosive chemicals]] [[Category:Inorganic compounds]] [[Category:Sulfur compounds]] [[Category:Nitrides]] [[ja:硫化窒素]] [[zh:四氮化四硫]]