Sulfur mononitride
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| Names | |||
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| Preferred IUPAC name
sulfur mononitride | |||
| Systematic IUPAC name
Azaniumylsulfanidylidyne | |||
Other names
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| Identifiers | |||
3D model (JSmol)
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| Abbreviations | (NS)(.) | ||
| ChEBI | |||
| ChemSpider | |||
| 660 | |||
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |||
| NS | |||
| Molar mass | 46.07 g·mol−1 | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Sulfur mononitride is an inorganic compound with the molecular formula NS. It is the sulfur analogue of and isoelectronic to the radical nitric oxide, NO. It was initially detected in outer space in giant molecular clouds and later the coma of comets. [1] Synthetically, it is produced by electric discharge in mixtures of nitrogen and sulfur compounds, or combustion in the gas phase and by photolysis in solution.[2]
Synthesis
The NS radical is a highly transient species, but it can be observed spectroscopically over short periods of time through several methods of generation.
Discharge of nitrogen and sulfur vapor
Transmitting uncondensed electric discharge through a glass tube with quartz windows containing a mixture of nitrogen and sulfur vapor (rigorously free of oxygen) results in the spectrum of emitted light gaining bands consistent with the formation of NS. [3]
Passing a mixture of gaseous N2 and S2Cl2 through the side arm of an absorption cell undergoing microwave discharge produces NS. Infrared diode laser spectroscopy taken using this method allowed for derivation of the equilibrium rotational constant, and therefore calculation of the equilibrium bond length as 1.4940 Å. [4]
Burning of sulfur and nitrogen doped flames
Methane was premixed with fuel in the form of either O2, N2O, or air and burned at ambient pressure. The source of nitrogen was introduced by addition of 1-5 mole% NH3 gas and sulfur by 0.01-0.5 mol% H2S or SF6 gas. A steady state concentration of NS within the flame front is observed by laser-induced fluorescence (LIF) spectrum. [5]
Flash laser photolysis of tetranitrogen tetrasulfide
N4S4 (g) was obtained by the following reaction:
Removal of byproducts leaves only N4S4 in toluene, which is through a gas inlet pipe into the reaction cell.
The NS radical was subsequently identified by LIF spectrum as the product of photolysis of N4S4 (g) by a 248 nm laser. [6]
Flash and continuous photolysis of Cr(CH3CN)5(NS)2+
Aerated solutions of Cr(CH3CN)5(NS)2+ are highly photoactive and prone to rapid decomposition. Deaerated solutions of Cr(CH3CN)5(NS)2+ in acetonitrile are stable as long as they are kept in the dark. Continuous photolysis using 366 nm light is slow, while using a 355 nm pulsed laser results in faster labilization of NS. [7]
Reactivity
Products of decay with NO2
The radical decay time of NS alone is on the order of 1-3 ms. As evident by no change to this decay time upon addition of NO or O2 at ambient temperatures, the NS radical is unreactive with NO and O2. However, rapid, first-order decay is observed with the addition of NO2. This reaction is proposed to proceed through various intermediates, ultimately reaching final products of N2 and SO2.
This rapid reaction occurs with a rate constant of k = (2.54 ± 0.12) × 10-11 cm3 molecules-1 s-1 at 295 K. By use of Density Functional Theory based computational calculations, the minima and transition states of the potential energy surface of this reaction have been predicted. [6]
Astronomical reactivity
Within the inner coma of comets, many reactions are theorized to be relevant to the formation and reactivity of the NS radical. [8]
Metal-thionitrosyl complexes
As a ligand, NS acts as a σ-donor and π-acceptor, forming metal-thionitrosyl complexes. Transition-metal thionitrosyl complexes have been prepared by the following procedures:
- Sulfur transfer to metal nitrido complexes
- Example: [OsN(NCS)5]2- + Ph4PSCN > [Ph4P]2[Os(NS)(NCS)5]
- Reaction of trithiazyltrichloride with transition metal complexes
- NSCl3 + OsCl3 > [Os(NS)Cl3]
- Halide abstraction from coordinated thiazyl complexes
- Abstraction of sulfur-bonded fluorine from [(η5-C5H5)Cr(NO)2(NSF)]-[AsF6] by AsF5 > [(η5-C5H5)Cr(NO)2(NS)]-[AsF6]2
- Reaction of NS+ salts with transition metal complexes
- NS+SbF6- + [Re(CO)5Br] > [Re(CO)5(NS)]2+
- NS+AsF6- + [(η5-C5H5)Fe(CO)2(SO2)]+ > [(η5-C5H5)Fe(CO)2(NS)][AsF6]2
- Reaction of tetrasulfur tetranitride with metal halides or nitrides
From X-ray crystallography of many of such metal-thionitrosyl complexes, one can observe that the M-N-S bond angle is nearly linear, suggesting sp hybridization about N. Short M-N distances and long N-S distances reflect the resonance structure of M=N=S having greater contribution than M-N≡S. [9]
Photoinduced NS transfer from chromium to iron
When a spin-trapping agent, such as Fe(S2CNEt2)2 is present during the photolysis of Cr(CH3CN)5(NS)2+, new S=1/2 EPR bands are observed, attributed to the formation of Fe(S2CNEt2)2(NS), and the signal from Cr(CH3CN)5(NS)2+ disappears. This suggests that the NS radical has transferred from the chromium complex to the iron complex. [7]
Bonding
The valence electrons of this compound match those of nitric oxide. Unlike NO, NS reacts upon condensation to form polythiazyl or tetrasulfur tetranitride. Sulfur mononitride can be described as some average of a set of resonance structures, one of which has a bond order of one accompanied by charge separation.[citation needed][clarification needed]
Related compounds
- Trithiazyl trichloride (NSCl)3
See also
References
- ^ Canaves, M. V.; de Almeida, A. A.; Boice, D. C.; Sanzovo, G. C. (March 2002). "Nitrogen Sulfide in Comets Hyakutake (C/1996 B2) and Hale-Bopp (C/1995 O1)". Earth, Moon, and Planets. 90 (1): 335–347. Bibcode:2002EM&P...90..335C. doi:10.1023/A:1021582300423. S2CID 189898818.
- ^ Burr, J. G. (1985). Chemi- and Bioluminescence. Clinical and Biochemical Analysis. Vol. 16. CRC Press. p. 99. ISBN 0-8247-7277-6.
- ^ "The band spectrum of nitrogen sulphide (NS)". Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character. 136 (829): 28–36. 1932-05-02. doi:10.1098/rspa.1932.0064. ISSN 0950-1207.
- ^ Matsumara, Keiji; Kawaguchi, Kentarou; Jagai, Keijchi; Yamada, Chikashi; Hirota, Eizi (1980). "Infrared Diode Laser Spectroscopy of the NS Radical". Journal of Molecular Spectroscopy (84): 68–73.
- ^ Jeffries, Jay; Crosley, David (1986). "Laser-Induced Fluorescence Detection of the NS Radical in Sulfur and Nitrogen Doped Methane Flames". Combustion and Flame (64): 55–64.
- ^ a b Blitz, Mark; McKee, Kenneth; Pilling, Michael; Vincent, Mark; Hillier, Ian (2002). "Experimental Rate Measurements for NS + NO, O2 and NO2, and Electronic Structure Calculations of the Reaction Paths for NS + NO2". J. Phys. Chem. 106 (36): 8406-841S.
- ^ a b Dethlefsen, Johannes; Hedegard, Erik; Rimer, R. Dale; Ford, Peter; Dossing, Anders (2009). "Flash and Continuous Photolysis Studies of the Thionitrosyl Complex Cr(CH3CN)5(NS)2+ and the Nitric Oxide Analogs: Reactions of Nitrogen Monosulfide in Solution". Inorganic Chemistry. 48 (1): 231–238.
- ^ Canaves, Marcus V.; De Almeida, Amaury A.; Boice, Daniel C.; Sanzovo, Gilberto C. (2002), "Nitrogen Sulfide in Comets Hyakutake (C/1996 B2) and Hale-Bopp (C/1995 O1)", Cometary Science after Hale-Bopp, Dordrecht: Springer Netherlands, pp. 335–347, ISBN 978-90-481-6156-0, retrieved 2022-12-15
- ^ Pandey, Krishna (1992). "Coordination Chemistry of Thionitrosyl (NS), Thiazate (NSO-), Disulfidothionitrate (S3N-), Sulfur Monoxide (SO), and Disulfur Monoxide (S2O) Ligands". Progress in Inorganic Chemistry. 40: 445–502.
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