They are thermodynamically unstable with respect to loss of elemental sulfur: Nonetheless, persulfides are often kinetically stable.
Thus, persulfides exist predominantly in the ionized form at neutral pH.
The S-S bond length is 204 picometers and the C-S-S-H dihedral angle is 82°.
Cystathionase generates the persulfide of cysteine (sometimes called thiocysteine) from cystine.
Persulfides have been invoked as intermediates in the biodegradation of carbon disulfide[4] and mercaptopyruvate.