English

Noun

1. any compound formally derived from hydrogen sulfide by replacing one hydrogen atom with a metal or other radical; a thiol or mercaptan
2. the HS- anion

Alternative spellings

• hydrosulphide

The Bisulfide (or Bisulphide in British English spelling) ion, also called hydrosulfide, is the anion with the formula [HS]− (commonly written [SH]−). This species is the conjugate base of hydrogen sulfide:

H2S HS− + H+

In aqueous solutions, at pH greater than 7, hydrogen sulfide is the dominant species; at pH > 7, bisulfide dominates.

A variety of salts are known, including sodium hydrosulfide and potassium hydrosulfide. Ammonium hydrosulfide, a component of "stink bombs" has not been isolated as a pure solid. Some compounds described as salts of the sulfide dianion contain primarily hydrosulfide. For example, the hydrated form of sodium sulfide, nominally with the formula Na2S·(H2O)9, is better described as NaSH·NaOH·(H2O)8. Aqueous bisulfide absorbs light at around 230nm in the UV/VIS spectrum. Groups have used field spectrometers to measure the absorption due to bisulfide (and hence its concentration) continuously in the ocean and in sewage. Bisulfide is sometimes confused with the disulfide dianion, S22−.

Coordination chemistry

SH− is a soft anionic ligand that forms complexes with most metal ions. Examples include [Au(SH)2]− and (C5H5)2Ti(SH)2, derived from gold(I) chloride and titanocene dichloride, respectively.

References