Fig. 2: Ar₄N⁺ salts reported in the literature.

Counter anions are depicted in the general form X. a Pentatritiated Ph₄N⁺ salts (1) reported without proper structural data. b Synthesis of (N,N-diphenyl)carbazolium salts (2) from precursor 3 following the process of intramolecular N-arylation. The bridge moiety indicated in blue must be removed to obtain the Ph₄N⁺ salts. c Other bridged Ar₄N⁺ salts such as (N,N-diphenyl)carbazolium salts (4) bearing various substituents Y on the aryl groups, spirobicarbazolium salts (5), sulfide-bridged Ar₄N⁺ salts (6), and amide-bridged Ar₄N⁺ salts (7) prepared following the intramolecular N-arylation strategy. The bridge moieties are indicated in blue.