amidium ions

https://doi.org/10.1351/goldbook.A00268
Cations formally derived by the addition of one hydron to the N or O atom of an amide and N-hydrocarbyl derivatives thereof. In organic chemistry an unspecified amidium ion is commonly a carboxamidium ion
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or
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The term does not imply knowledge concerning the position of the cationic centre, e.g.
PhC(=O)N+Me3
N,N,N-trimethylbenzamidium.
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1315 (https://doi.org/10.1351/pac199567081307)
See also:
PAC, 1993, 65, 1357. 'Revised nomenclature for radicals, ions, radical ions and related species (IUPAC Recommendations 1993)' on page 1357 (https://doi.org/10.1351/pac199365061357)