1-Iodonaphthalene-2,4-diamines in trifluoroacetic acid/chloroform give stable Wheland-like tetrahedral cationic species observable by NMR, through an initial intramolecular protonation. Dynamic equilibria allow proton-deuterium exchange of aromatic protons and provide a mechanism for deiodination of 1-iodonaphthalene-2,4-diamines.