The lower sulfur

Sulfur

Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 oxide

Oxide

An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....

s are a group of chemical compounds consisting of :

• SO, sulfur monoxide
  Sulfur monoxide
  Sulfur monoxide is an inorganic compound with formula . It is only found as a dilute gas phase. When concentrated or condensed, it converts to S2O2 . It has been detected in space but is rarely encountered intact otherwise.-Structure and bonding:The SO molecule has a triplet ground state similar...
  
   and its dimer S₂O₂
• S₂O
• sulfur monoxides, S_nO, based on cyclic S_n rings where n is 5-10
• S₇O₂
• polymeric oxides, polysulfuroxides sometimes termed PSO's

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

Io (moon)

Io ) is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of , the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus....

, one of Jupiter

Jupiter

Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

s moons, and Venus

Venus

Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...

 contain significant amounts of sulfur oxides.
Some compounds reported by early workers such as the blue "sesquioxide", S₂O₃, formed by dissolving sulfur in liquid SO₃ appears to be a mixture of polysulfate salts of the S₄²⁺ and S₈²⁺ ions.

Sulfur monoxide

Sulfur monoxide

Sulfur monoxide is an inorganic compound with formula . It is only found as a dilute gas phase. When concentrated or condensed, it converts to S2O2 . It has been detected in space but is rarely encountered intact otherwise.-Structure and bonding:The SO molecule has a triplet ground state similar...

, monomer (SO) and dimer (S₂O₂)

These are stable molecules that have been trapped at low temperature (see sulfur monoxide article

Sulfur monoxide

Sulfur monoxide is an inorganic compound with formula . It is only found as a dilute gas phase. When concentrated or condensed, it converts to S2O2 . It has been detected in space but is rarely encountered intact otherwise.-Structure and bonding:The SO molecule has a triplet ground state similar...

).

Disulfur monoxide

Disulfur monoxide

Disulfur monoxide or sulfur suboxide is an unstable gas being a compound of sulfur and oxygen with formula S2O. It is one of the lower sulfur oxides. It is a colourless gas. It can be formed by reacting thionyl chloride with silver sulfide:...

, S₂O

S₂O has a non linear structure, like sulfur dioxide

Sulfur dioxide

Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

, SO₂, ozone

Ozone

Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

, O₃ and S₃. The S-S bond is 188.4pm, the S-O bond is 146.5pm and the SSO angle is 117.88. The two dipole moment components are μa = 0.875D and μb = 1.18D

Trisulfur monoxide, S₃O

This unstable neutral molecule has been found in the gas phase using neutralization-reionization mass spectrometry. Both ring and chain structures were found.

S_nO

A number of monoxides S_nO are known where n= 5-10, where the oxygen is bonded to one member of the S_n sulfur ring. They can be prepared by oxidising the related cyclo-S_n elemental sulfur rings (these are allotropes of sulfur

Allotropes of sulfur

There are a large number of allotropes of sulfur. In this respect, sulfur is second only to carbon.The most common form found in nature is yellow orthorhombic α-sulfur, which contains puckered rings of . Chemistry students may have seen "plastic sulfur"; this is not an allotrope but a mixture of...

) with trifluoroperoxoacetic acid, CF₃C(O)OOH. The compounds are all dark coloured and decompose to give sulfur and sulfur dioxide.

S₆O₂, S₇O₂

S₆O₂ and S₇O₂ can be prepared by oxidising cyclo-S₆ and cyclo-S₇ respectively, with trifluoroperoxoacetic acid, although crystalline S₆O₂ has not been isolated.

Polymeric sulfuroxides

These have been studied to determine whether they are a factor in the observed colour of Io

Io (moon)

Io ) is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of , the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus....

.