The lower sulfur oxides are a group of
inorganic compounds
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''.
Inorg ...
with the formula , where 2''m'' > ''n''. These species are often unstable and thus rarely encountered in everyday life. They are significant intermediates in the combustion of elemental sulfur.
Some well characterized examples include
sulfur monoxide (SO), its dimer , and a series of cyclic sulfur oxides, (''x'' = 1, 2), based on cyclic rings.
Interest in the lower sulfur oxides has increased because of the need to understand terrestrial atmospheric sulfur pollution and the finding that the extraterrestrial atmospheres of
Io, one of
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
's moons, and
Venus
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...
contain significant amounts of sulfur oxides.
Some compounds reported by early workers such as the blue "
sesquioxide", , formed by dissolving sulfur in liquid appears to be a mixture of polysulfate salts of the and ions.
Sulfur monoxide, disulfur dioxide, disulfur monoxide
These species are well characterized in the gas phase, but they cannot be isolated as solids or liquids. Instead, when condensed, they undergo dimerization and oligomerization, usually yielding sulfur dioxide and elemental sulfur. At a few
millibars pressure, the relative stabilities are > > SO.
[ Sulfur monoxide (SO) and its dimer () have been trapped at low temperature. Disulfur dioxide () is a dimer of sulfur monoxide. It has C2v structure (planar).
Disulfur monoxide () is an analogue of ]sulfur dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
. Like as well as ozone
Ozone () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...
(), and trisulfur (), it adopts a bent structure. The S-S bond length
In molecular geometry, bond length or bond distance is defined as the average distance between Atomic nucleus, nuclei of two chemical bond, bonded atoms in a molecule. It is a Transferability (chemistry), transferable property of a bond between at ...
is 188.4 pm, the S-O bond is 146.5 pm and the SSO angle is 117.88°. The two dipole moment components are μa = 0.875 D and μb = 1.18 D. This species decomposes to give a polymeric sulfur oxides ("PSO's") with the approximate formula . PSO's decompose at room temperature to elemental sulfur and . PSO's have been proposed to be responsible for the colour of Io.
Trisulfur monoxide, is an unstable molecule. It has been detected in the gas phase using neutralization-reionization mass spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used ...
. Both cyclic and chain structures were found.
Cyclic (''x'' = 1, 2)
A number of monoxides are known where ''n'' = 5-10. The oxygen atom is exocyclic.
References
{{reflist
Sulfur oxides
Interchalcogens