sulfenic acids

https://doi.org/10.1351/goldbook.S06096
Compounds having the structure RSOH (RH), e.g. PhSOH benzenesulfenic acid.
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1368 (https://doi.org/10.1351/pac199567081307)