Persulfide
In chemistry, persulfide refers to the functional group R-S-S-H.[1] Persulfides are intermediates in the biosynthesis of iron-sulfur proteins and are invoked as precursors to hydrogen sulfide, a signaling molecule.
Nomenclature
The nomenclature used for organosulfur compounds is often non-systematic. Sometimes persulfides are called hydrodisulfides to further avoid confusion with
Properties
Compared to thiols (R-S-H), persulfides are uncommon. They are thermodynamically unstable with respect to loss of elemental sulfur:
- RSSH → RSH + 1/8 S8
Nonetheless, persulfides are often kinetically stable.
The S-H bond is both more acidic and more fragile than in thiols. This can be seen in the
Structure and reactions
The structure of trityl persulfide has been determined by X-ray crystallography. The S-S bond length is 204 picometers and the C-S-S-H dihedral angle is 82°. These parameters are unexceptional.[2] (C6H5)3CSSH behaves as a source of sulfur, illustrated by its reaction with triphenylphosphine to give triphenylphosphine sulfide and triphenylmethanethiol:
- (C6H5)3CSSH + P(C6H5)3 → (C6H5)3CSH + SP(C6H5)3
Biosynthetic and catabolic roles
The cofactors
Persulfides have been invoked as intermediates in the biodegradation of carbon disulfide[3] and mercaptopyruvate.
References
- ^ PMID 25969163.
- PMID 25010540.
- PMID 238535.)
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