Compounds having the structures
RS2H,
RS3H ...
RSnH, in which
Sn is a chain of sulfur atoms, and
R is hydrocarbyl. Some people exclude hydrodisulfides from the class hydropolysulfides.
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1342 (https://doi.org/10.1351/pac199567081307)