Sulfursulfur

Sulfursulfur is a term that has appeared in some sources to designate the diatomic sulfur molecule, S2. In contemporary chemical practice, the molecule is more commonly called disulfur or sulfur dimer, while sulfursulfur is a historical or informal name. The species consists of two sulfur atoms connected by a covalent bond and is the simplest sulfur-containing molecule that can exist in the gas phase, though it is not stable at standard conditions.

Structure and properties: S2 has a single S–S bond with a bond length of about 1.9 Å. The bond is relatively weak compared with bonds in more complex sulfur-containing compounds, and S2 is predominantly a transient species in high-temperature environments. Under cooling, S2 tends to convert back into the more stable allotropes of sulfur, such as S8 rings.

Formation and reactions: S2 forms in the gas phase at elevated temperatures, such as in flames, volcanic plumes, or during rapid sulfur pyrolysis. It readily reacts with oxygen to give sulfur monoxide (SO) and, with further oxidation, sulfur dioxide (SO2) and potentially sulfur trioxide (SO3) under appropriate conditions. In reducing environments, S2 can participate in the formation of larger sulfur-containing clusters or polymerize upon cooling.

Occurrence and detection: S2 is detected by spectroscopic methods, including UV–visible absorption and Raman spectroscopy, in high-temperature combustion gases and volcanic emissions. Its transient nature makes it a subject of study mainly in physical chemistry, combustion science, and planetary or astrophysical contexts.

Safety: handling sulfur-containing gases requires ventilation and appropriate protective equipment, as reactive sulfur species can irritate the respiratory tract and interact with oxidizers.

See also: elemental sulfur allotropes; sulfur oxides; disulfur.