Disulfur dioxide explained

Disulfur dioxide, dimeric sulfur monoxide or SO dimer is an oxide of sulfur with the formula S2O2.[1] The solid is unstable with a lifetime of a few seconds at room temperature.[2]

Structure

Disulfur dioxide adopts a cis planar structure with C2v symmetry. The S−O bond length is 145.8 pm, shorter than in sulfur monoxide. The S−S bond length is 202.45 pm and the O−S−S angle is 112.7°. S2O2 has a dipole moment of 3.17 D. It is an asymmetric top molecule.[3] [4]

Formation

Sulfur monoxide (SO) converts to disulfur dioxide (S2O2) spontaneously and reversibly.[5] So the substance can be generated by methods that produce sulfur monoxide. Disulfur dioxide has also been formed by an electric discharge in sulfur dioxide.[4] Another laboratory procedure is to react oxygen atoms with carbonyl sulfide or carbon disulfide vapour.[6]

Although most forms of elemental sulfur (S8 and other rings and chains) do not combine with SO2, atomic sulfur does so to form sulfur monoxide, which dimerizes:[7]

S + SO2 → S2O2 ⇌ 2 SO

Disulfur dioxide is also produced upon a microwave discharge in sulfur dioxide diluted in helium. At a pressure of, five percent of the result is S2O2.[8]

Disulfur dioxide is formed transiently when hydrogen sulfide and oxygen undergo flash photolysis.[9]

Properties

The ionization energy of disulfur dioxide is .[6]

Disulfur dioxide absorbs at 320–400 nm, as observed of the Venusian atmosphere,[10] and is believed to have contributed to the greenhouse effect on that planet.[11]

Reactions and decomposition

Although disulfur dioxide exists in equilibrium with sulfur monoxide, it also reacts with sulfur monoxide to form sulfur dioxide and disulfur monoxide.[12] [13]

Decomposition of S2O2 proceeds via the following disproportionation reaction:

Complexes

S2O2 can be a ligand with transition metals. It binds in the η2-S–S position with both sulfur atoms linked to the metal atom.[14] This was first shown in 2003. The bis(trimethylphosphine) thiirane S-oxide complex of platinum, when heated in toluene at 110 °C loses ethylene, and forms a complex with S2O2: (Ph3P)2Pt(S2O2).[15] Iridium atoms can also form a complex: cis-[(dppe)<sub>2</sub>IrS<sub>2</sub>]Cl with sodium periodate oxidizes to [(dppe)<sub>2</sub>IrS<sub>2</sub>O] and then to [(dppe)<sub>2</sub>IrS<sub>2</sub>O<sub>2</sub>], with dppe being 1,2-bis(diphenylphosphino)ethane.[16] [17] This substance has the S2O2 in a cis position. The same conditions can make a trans complex, but this contains two separate SO radicals instead. The iridium complex can be decomposed with triphenylphosphine to form triphenylphosphine oxide and triphenylphosphine sulfide.[16]

Anion

The radical anion has been observed in the gas phase. It may adopt a trigonal shape akin to SO3.[18]

Spectrum

Microwave

TransitionFrequency (MHz)
21,1−20,211013.840
41,3−40,414081.640
11,1−00,015717.946
40,4−31,316714.167
31,3−20,226342.817
42,2−41,326553.915
22,0−21,128493.046
60,6−51,530629.283
52,4−51,535295.199
51,5−40,435794.527

In the Solar System

There is some evidence that disulfur dioxide may be a small component in the atmosphere of Venus, and that it may substantially contribute of the planet's severe greenhouse effect.[10] It is not found in any substantive quantity in Earth's atmosphere.

Notes and References

  1. Book: Arnold F. . Holleman . Egon . Wiber . Nils . Wiberg . Inorganic Chemistry. https://books.google.com/books?id=Mtth5g59dEIC&pg=PA530. 2001. Academic Press. 530. Oxides of sulfur. 9780123526519 .
  2. Book: Mitchell, Stephen C. . Biological Interactions Of Sulfur Compounds. 2004. CRC Press. 9780203362525. 7.
  3. Book: Demaison. Jean. Vogt. Jürgen. Asymmetric Top Molecules, Part 3. https://link.springer.com/content/pdf/10.1007%2F978-3-642-14145-4_258.pdf. Landolt–Börnstein: Group II Molecules and Radicals. 10.1007/978-3-642-14145-4_258. 29D3. 2011. Springer. 9783642141454. 492 . 836. O2S2 Disulfur dioxide.
  4. Thorwirth. Sven. P.. Theulé. C. A.. Gottlieb . H. S. P.. Müller. M. C.. McCarthy. P.. Thaddeus. 2006. Rotational spectroscopy of S2O: vibrational satellites, 33S isotopomers, and the submillimeter-wave spectrum. 219–229. 795. 1–3. Journal of Molecular Structure. 10.1016/j.molstruc.2006.02.055. 2006JMoSt.795..219T.
  5. 10.1063/1.1681015 . 60 . Spectroscopic studies of the SO2 discharge system. II. Microwave spectrum of the SO dimer . 1974 . The Journal of Chemical Physics . 5005 . Lovas . F. J.. 12 . 1974JChPh..60.5005L .
  6. Cheng. Bing-Ming. Wen-Ching. Hung. 1999. Photoionization efficiency spectrum and ionization energy of S2O2. The Journal of Chemical Physics. 110. 1. 188. 0021-9606. 10.1063/1.478094. 1999JChPh.110..188C.
  7. Murakami. Yoshinori . Shouichi . Onishi . Takaomi . Kobayashi . Nobuyuki . Fujii . Nobuyasu . Isshiki . Kentaro . Tsuchiya . Atsumu . Tezaki . Hiroyuki . Matsui. 2003. High Temperature Reaction of S + SO2 → SO + SO: Implication of S2O2 Intermediate Complex Formation. The Journal of Physical Chemistry A. 107. 50. 10996–11000. 1089-5639. 10.1021/jp030471i. 2003JPCA..10710996M .
  8. Book: Sahoo. Balaram. Nayak. Nimai Charan. Samantaray. Asutosh. Pujapanda. Prafulla Kumar. Inorganic Chemistry. 2013-05-16. PHI Learning. 9788120343085. 461. 2012.
  9. Book: Compton. R. G.. Bamford. C. H. . Tipper. C. F. H. . Reactions of Non-Metallic Inorganic Compounds. https://books.google.com/books?id=GwhMyI_tZO4C. Comprehensive Chemical Kinetics. 1972. Elsevier. 9780080868011. 50. Oxidation of H2S.
  10. Identification of OSSO as a near-UV absorber in the Venusian atmosphere. B. N.. Frandsen. P. O.. Wennberg. H. G.. Kjærgaard. 2016. Geophysical Research Letters. 43. 21. 11146–11155. 10.1002/2016GL070916. 2016GeoRL..4311146F. free.
  11. Web site: Rare molecule on Venus may help explain planet's weather . CBC News . 2016-11-11.
  12. Field. T. A.. A. E.. Slattery. D. J.. Adams. D. D.. Morrison. 2005. Experimental observation of dissociative electron attachment to S2O and S2O2 with a new spectrometer for unstable molecules. Journal of Physics B: Atomic, Molecular and Optical Physics. 38. 3. 255–264. 0953-4075. 10.1088/0953-4075/38/3/009. 2005JPhB...38..255F. 122789729 . 2013-05-13. https://web.archive.org/web/20150924110541/http://www.qub.ac.uk/schools/SchoolofMathematicsandPhysics/ampr/tfield/reprint-eric1.pdf. 2015-09-24. dead.
  13. Herron. J. T.. R. E.. Huie. 1980. Rate constants at 298 K for the reactions SO + SO + M → (SO)2 + M and SO + (SO)2 → SO2 + S2O. Chemical Physics Letters. 76. 2. 322–324. 10.1016/0009-2614(80)87032-1. 1980CPL....76..322H.
  14. Halcrow. Malcolm A.. John C.. Huffman. George. Christou. 1994. Synthesis, Characterization, and Molecular Structure of the New S2O Complex Mo(S2O)(S2CNEt2)3·1/2Et2O. Inorganic Chemistry. 33. 17. 3639–3644. 0020-1669. 10.1021/ic00095a005. 2013-05-13. 2015-11-06. https://web.archive.org/web/20151106083617/http://www.chem.ufl.edu/~christou/group/ChristouGroupPapers/138%20Mo%20S2O%20full%20IC.pdf. dead.
  15. Lorenz. Ingo-Peter. Jürgen. Kull. 1986. Complex Stabilization of Disulfur Dioxide in the Fragmentation of Thiirane S-Oxide on Bis(triphenylphosphane)platinum(0). Angewandte Chemie International Edition in English. 25. 3. 261–262. 0570-0833. 10.1002/anie.198602611.
  16. Schmid. Günter. Günter. Ritter. Tony. Debaerdemaeker. 1975. Die Komplexchemie niederer Schwefeloxide. II. Schwefelmonoxid und Dischwefeldioxid als Komplexliganden. The complex chemistry of lower sulfur oxides. II. Sulfur monoxide and disulfur dioxide as complex ligands. Chemische Berichte. 108. 9. 3008–3013. 0009-2940. 10.1002/cber.19751080921.
  17. Nagata. K.. N.. Takeda. N.. Tokitoh. 2003. Unusual Oxidation of Dichalcogenido Complexes of Platinum. Chemistry Letters. 32. 2. 170–171. 0366-7022. 10.1246/cl.2003.170.
  18. Clements. Todd G. . Hans-Jürgen Deyerl . Robert E. Continetti. 2002. Dissociative Photodetachment Dynamics of . The Journal of Physical Chemistry A. 106. 2. 279–284. 1089-5639. 10.1021/jp013329v. 2013-05-13. 2002JPCA..106..279C .

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