Disulfur monoxide

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Disulfur monoxide
Structure of S2O
solid ball model of S2O
Names
Other names
sulfur suboxide; sulfuroxide;
Identifiers
3D model (
JSmol
)
ChemSpider
  • [1]: InChI=1S/OS2/c1-3-2
    Key: TXKMVPPZCYKFAC-UHFFFAOYSA-N
  • O=S=S
Properties
S2O
Molar mass 80.1294 g/mol[1]
Appearance colourless gas or dark red solid[2]
Structure
bent
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 toxic
Related compounds
Related compounds
 Trisulfur
SO
Ozone
SO2
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Disulfur monoxide or sulfur suboxide is an inorganic compound with the formula S2O, one of the lower sulfur oxides. It is a colourless gas and condenses to give a roughly dark red coloured solid that is unstable at room temperature.

S
2O occurs rarely in natural atmospheres, but can be made by a variety of laboratory procedures. For this reason, its spectroscopic signature is very well understood.

Structure and spectrum

Condensed solid S2O

S4.[3]

In the ultraviolet, S2O has absorption band systems in the ranges 250–340 nm and 190–240 nm. There are bands at 323.5 and 327.8 nm.[4] The band in the 315–340 nm range is due to the C1A′–X1A′ (π* ← π) transition.[5]

Gaseous disulfur monoxide does not absorb light in the visible spectrum.

The microwave spectrum of S2O has the following rotational parameters: A = 41915.44 MHz, B = 5059.07 MHz, and C = 4507.19 MHz.[6] Moreover, the microwave spectrum suggests the S−S−O angle is 117.88° with S−S and S−O bond lengths of 188.4 and 146.5 pm, respectively.[7] In the 327.8 nm excited state, the central angle tightens to 109°.[4]

The

harmonic frequency for S−S stretching is 415.2 cm−1.[5]

Synthesis

Historical

Disulfur monoxide was discovered by Peter W. Schenk in 1933[8] with a glow discharge though sulfur vapour and sulfur dioxide. He discovered that the gas could survive for hours at single digit pressures of mercury in clean glass, but it decomposed near 30 mmHg (4 kPa). Schenk assigned the formula as SO and called it sulfur monoxide. In 1956, D. J. Meschi and R. J. Myers established the formula as S2O.[9]

Preparation

Oxidizing sulfur with copper(II) oxide:[10][11]

3 S8 + 12 CuO → 12 CuS + 4 S2O + 4 SO2

A relatively pure generator is the reaction of

silver(I) sulfide:[12]

SOCl2 + Ag2S → 2 AgCl + S2O

Also 5,6-di-tert-butyl-2,3,7-trithiabicyclo[2.2.1]hept-5-ene 2-endo-7-endo-dioxide decomposes upon heating with release of S2O:[13]

Occurrence

Volcanism

Volcanoes on Io produce substantial quantities of S
2O. It can form between 1% and 6% when hot 100-bar S2 and SO2 gas erupts from volcanoes. It is believed that Pele on Io is surrounded by solid S2O.[14]

Terran atmosphere

Disulfur monoxide is too unstable to survive at standard conditions,

incomplete combustion of sulfur vapor[15] and thermal decomposition of sulfur dioxide in a glow discharge.[16]

As a ligand

Disulfur monoxide occurs as a

transition metal sulfur dioxide complexes
.

Reactions

On decomposition at room temperature it forms SO2 via the formation of polysulfur oxides:[16]

2 S2O → "S3" + SO2

S
2O reacts with

diazoalkanes to form dithiirane 1-oxides.[19]

Further reading

References

  1. ^ a b c "Disulfur monoxide". NIST. 2008.
  2. doi:10.1016/0019-1035(89)90107-3
    .
  3. doi:10.1016/j.cplett.2010.10.012
    .
  4. ^
    doi:10.1139/p77-226
    .
  5. ^
    doi:10.1063/1.469623
    .
  6. doi:10.1016/0022-2852(73)90042-8
    .
  7. doi:10.1016/0022-2852(59)90036-0
    .
  8. ^
    ISBN 9783540449515
    .
  9. doi:10.1021/ja01605a002
    .
  10. S2CID 91428580. Archived from the original
    (PDF) on 2014-10-17. Retrieved 2013-11-08.
  11. ISSN 0022-3263
    .
  12. ISSN 1521-3773
    .
  13. PMID 15264842
    .
  14. doi:10.1006/icar.1998.5930. Archived from the original
    (PDF) on 10 October 2017. Retrieved 2 October 2010.
  15. ^ Khan, Ashikur R. (August 1999). Experimental Studies of the Homogenous Conversion of Sulfur Di-Oxide to Sulfur Tri-Oxide via Natural Gas Reburning (Thesis). Ohio University. p. 8. Other sulfur oxides are sulfur monoxide, SO, its dimer, (SO)
    z    , and disulfur monoxide, S
    2    O    . These are too unstable or reactive to appear as products of combustion in the ordinary sense, but they are known to occur as intermediates in appropriate circumstances.
  16. ^ a b Cotton and Wilkinson (1966). Advanced Inorganic Chemistry: A Comprehensive Treatise. p. 540.
  17. ^
    ISSN 0276-7333
    .
  18. ISBN 978-0-470-16698-7
    .
  19. PMID 11385674
    .
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