trimethylenemethanes

https://doi.org/10.1351/goldbook.T06500
The @[email protected] CH2=C(C·H2)2, 2-methylenepropane-1,3-diyl, for which no Kekulé structure can be written, and its @[email protected] derivatives.
Source:
PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1373 [Terms] [Paper]