Stabilization of 2,6-Diarylanilinum Cation by Through-Space Cation−π Interactions

[Image: see text] Energetically favorable cation−π interactions play important roles in numerous molecular recognition processes in chemistry and biology. Herein, we present synergistic experimental and computational physical–organic chemistry studies on 2,6-diarylanilines that contain flanking meta/para-substituted aromatic rings adjacent to the central anilinium ion. A combination of measurements of pK(a) values, structural analyses of 2,6-diarylanilinium cations, and quantum chemical analyses based on the quantitative molecular orbital theory and a canonical energy decomposition analysis (EDA) scheme reveal that through-space cation−π interactions essentially contribute to observed trends in proton affinities and pK(a) values of 2,6-diarylanilines.