Electrostatic Potential at the Iodine Nucleus as a Predictive Descriptor for Lewis Acidity in Diaryliodonium Ions

Diaryliodonium salts are versatile hypervalent iodine(III) compounds whose utility as Lewis acid catalysts relies on the tunable electrophilicity of the iodine center. To enable the rational design of these catalysts, a predictive and computationally accessible electronic descriptor is essential. This study introduces the electrostatic potential at the iodine nucleus (V_I) as a robust, quantitative metric to evaluate the Lewis acidity across diverse acyclic and cyclic diaryliodonium architectures. Computed V_I values of diaryliodonium ions correlate strongly with established experimental benchmarks, including Gutmann-Beckett ³¹P NMR chemical shifts and a previously reported experimental acidity scale. Systematic analysis reveals that V_I sensitively captures electronic perturbations from the substituents and ring strain. A multiple linear regression model incorporating V_I and the C-I-C bond angle (Φ) successfully predicts Lewis acidity parameters for both acyclic and cyclic diaryliodonium ions on a single unified scale. This work establishes V_I as a fundamental and convenient parameter for assessing Lewis acidity, providing a clear electronic design principle for developing next-generation hypervalent iodine-based catalysts.