carbene radical cations

https://doi.org/10.1351/goldbook.C00810
Species R2C.+ having one non-bonding electron, formally derived by subtraction of an electron from a carbene, e.g. H2C.+ methyliumyl.
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1324 (https://doi.org/10.1351/pac199567081307)