alkanium ions

https://doi.org/10.1351/goldbook.A00223
Carbocations derived from @[email protected] by C-hydronation containing at least one pentacoordinate carbon atom, e.g. +CH5 methanium, [C2H7]+ ethanium.
See also:
carbonium ions
Source:
PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1313 [Terms] [Paper]