diradicals 

https://doi.org/10.1351/goldbook.D01765
Molecular species having two unpaired electrons, in which at least two different electronic states with different multiplicities [electron-paired (singlet state) or electron-unpaired (triplet state)] can be identified, e.g. H2C·–CH2–C·H2 propane-1,3-diyl (trimethylene).
See also: biradical
Source:
PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1333 [Terms] [Paper]
Citation: 'diradicals' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.D01765 RIS BibTex EndNote
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Last revised: February 24, 2014