Polythiazyl

Structural formula
General
Surname	Polythiazyl
other names	Polysulfur nitride Polyazasulfen
CAS number	56422-03-8
Monomer	S 2 N 2
Molecular formula of the repeating unit	SN
Molar mass of the repeating unit	46.07 g mol −1
Brief description	metallic-golden shiny crystals
properties
Physical state	firmly
Melting point	130 ° C
solubility	insoluble in water and organic solvents
safety instructions
GHS labeling of hazardous substances no classification available H and P phrases H: see above P: see above
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Polythiazyl is an inorganic chemical compound from the group of covalent nitrides . The compound is one next to the disulfur dinitride , the Tetraschwefeldinitrid , the tetrasulfur tetranitride , the Pentaschwefelhexanitrid , the Monoschwefelmononitrid , the Monoschwefeldinitrid and Oligoschwefeldinitriden to the group of sulfur-nitrogen compounds or Schwefelnitride . The polymeric inorganic and electrically conductive compound shows superconductivity at very low temperatures.

history

The compound was first described in 1910 by FP Burt, who obtained it by heating tetrasulfur tetranitride in a vacuum over silver wool.

The compound was the first non-metal compound in which superconductivity could be demonstrated. However, the transition temperature is relatively low at 0.3 K, which makes no practical application likely.

Extraction and presentation

The connection is created by the polymerisation of the disulfur dinitride, which is only stable at low temperatures. When the white starting material is slowly heated to −10 ° C, a deep blue, radical and paramagnetic intermediate consisting of open-chain NSNS units is created, which then converts to crystalline polymeric polythiazyl within two to three days. Polythiazyl can also be produced by means of vacuum pyrolysis of tetrasulfur tetranitride on silver wool at 300 ° C., with the disulfur dinitride occurring as an intermediate. A synthetic route that avoids the explosive starting materials S ₂ N ₂ and S ₄ N ₄ is the reaction of trithiazyl trichloride (NSCl) ₃ with trimethylsilyl azide . The trithiazyl trichloride can be obtained from disulfur dichloride , ammonium chloride and chlorine .

${\displaystyle \mathrm {4\,S_{2}Cl_{2}+2\,NH_{4}Cl\rightarrow [S_{3}N_{2}Cl]Cl+8\,HCl+5/8\,S_{8}} }$

${\displaystyle \mathrm {3\,[S_{3}N_{2}Cl]Cl+3\,Cl_{2}\rightarrow 2\,(NSCl)_{3}+3\,SCl_{2}} }$

${\displaystyle \mathrm {1/3\,(NSCl)_{3}+Me_{3}SiN_{3}\rightarrow 1/x\,(SN)_{x}+3/2\,N_{2}+Me_{3}SiCl} }$

properties

Polythiazyl is a metallic-golden, shiny, crystalline material that is fibrous. The polymer is relatively inert to oxygen and water , but decomposes to a gray powder in air. Explosive decomposition can occur at temperatures above 240 ° C. The connection also explodes when hit .

The structure of the crystalline compound could be elucidated by means of X-ray diffraction . This resulted in alternating SN bond lengths of 159 pm and 163 pm, as well as SNS bond angles of 120 ° C and NSN bond angles of 106 ° C.

The material has an anisotropic electrical conductivity. The connection is electrically conductive along the fibers or SN chains; perpendicular to it, it is an insulator. The one-dimensional conductivity is based on the bond conditions in the S – N chain, where each sulfur atom supplies two π electrons and each nitrogen atom supplies one π electron to form two-center 3π electron bond units.

Two polymorphic crystal forms were observed in the compound . The monoclinic Form I resulting from the synthesis can be converted to an orthorhombic Form II by mechanical treatment such as milling .

use

Due to its electrical conductivity, polythiazyl can be used as a material for LEDs , transistors , battery cathodes and solar cells .

literature

King, RSP: Novel chemistry and applications of polythiazyl , Doctoral Thesis Loughborough University 2009, PDF download

Individual evidence

1. ↑ ^{a b c d e f g h i j} Alsfasser, R .; Janiak, C .; Klapötke, TM; Meyer, H.-J .: Modern Inorganic Chemistry , editor Riedel, E., 3rd edition 2007, Walter de Gruyter GmbH & Co. KG, Berlin / Boston, ISBN 978-3-11-019060-1 , p. 129 –132, (accessed via De Gruyter Online).
2. ↑ ^{a b c} Wiberg, E .; Wiberg, N .; Holleman, AF : Inorganische Chemie , 103rd edition, 2017 Walter de Gruyter GmbH & Co. KG, Berlin / Boston, ISBN 978-3-11-026932-1 , p. 681, (accessed via De Gruyter Online).
3. ↑ ^{a b c} Entry on sulfur-nitrogen compounds. In: Römpp Online . Georg Thieme Verlag, accessed on March 2, 2017.
4. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
5. ↑ Burt, FP: A new sulphide of nitrogen in J. Chem. Soc. , Trans, 97 (1910) 1171-1174, doi : 10.1039 / CT9109701171 .
6. ↑ Labes, MM; Love, P .; Nichols, LF: Polysulfur nitride - a metallic, superconducting polymer in Chem. Rev. 79 (1979) 1-15, doi : 10.1021 / cr60317a002 .
7. ↑ ^{a b} MacDiarmid, AG; Mikulski, CM; Saran, MS; Russo, PJ; Cohen, MJ; Bright, AA; Garito, AF; Heeger, AJ: Synthesis and Selected Properties of Polymeric Sulfur Nitride, (Polythiazyl), (SN) _x in Advances in Chemistry 150 (2009) 63-72, doi : 10.1021 / ba-1976-0150.ch006 .
8. ↑ Boudeulle, M .: in Cryst. Struct. Comm. 4 (1975) 9-13.
9. ^ MacDiarmid, AG; Mikulski, CM; Russo, PJ; Saran, MS; Garito, AF; Heeger, AJ: Synthesis and structure of the polymeric metal, (SN) _x , and its precursor, S ₂ N ₂ in J. Chem. Soc. Chem. Comm. 1975, 476-477, doi : 10.1039 / C39750000476 .
10. ↑ Baughman, RH; Apgar, PA; Chance, RR; MacDiarmid, AG; Garito, AF: A New Phase of (SN) _x in J. Chem. Soc. Chem. Comm. 1977, 49-50, doi : 10.1039 / C39770000049 .
11. ↑ Ronald D. Archer: Inorganic and Organometallic Polymers . John Wiley & Sons, February 26, 2001, ISBN 978-0-471-24187-4 , p. 213 (Retrieved June 29, 2012).