We interrogated the mechanism of DABCO N-arylation via a range of kinetic and DFT experiments (Scheme 1c). We have conducted kinetic studies via variable-time-normalization analysis (VTNA), and established temperature-dependent thermodynamic and kinetic parameters via van't Hoff and Arrhenius plots; probed the speciation of diaryliodonium salts by conductivity and the thermodynamic interaction of diaryliodonium salts with Lewis bases by 1 H NMR titration experiments. Computational studies provide further insight into the nature of bonding interactions in reactive intermediates and transition states. New insight based on these studies has the potential for reaction design with diaryliodonium salts and broader application of ligand coupling across the p-block. Scheme 1. Strategies and mechanistic insight for nucleophile arylation.