carbenes having a vinylic group on a carbenic carbon atom
R2C=CRC:R↔︎
R2C+–CR=C−R. E.g.
H2C=CHC:H prop-2-en-1-ylidene.
See: 1,3-dipolar compounds
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1374 (https://doi.org/10.1351/pac199567081307)