Compounds having the structure
RS(=O)2OS(=O)2R',
e.g.
PhS(=O)2OS(=O)2Ph
benzenesulfonic anhydride.
Source:
PAC, 1995, 67, 1307
(Glossary of class names of organic compounds and reactivity intermediates based on
structure (IUPAC Recommendations 1995))
on page 1369