alkanium ions

https://doi.org/10.1351/goldbook.A00223
Carbocations derived from alkanes by C-hydronation containing at least one pentacoordinate carbon atom, E.g. +CH5 methanium, [C2H7]+ ethanium.
See also: carbonium ion
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1313 (https://doi.org/10.1351/pac199567081307)