Theoretical Quantification of the Lewis Acidity of N‐Heterocyclic Iodonium Salts

The quantitative Lewis acidity of N-heterocyclic iod(az)olium salts is helpful for their further application in organic chemistry. The acidity scales of different N-Heterocyclic iodonium salts (NHISs) in acetonitrile are investigated using Density functional theory (DFT) studies. There are a total of 121N-Heterocyclic iodonium salts that have been designed by combining N-heterocyclic and iodonium salt structures in this research. Theoretical calculations systematically established the P-31 NMR chemical shifts of NHISs, and the relative Lewis acidity scale was derived. The Lewis acidity trend is analyzed and explained by the natural population analysis (NPA) charges, molecular electrostatic potential, and the interaction between the iodonium center and the N-heterocyclic substituents. This study is expected to provide a practical quantitative theoretical scale for the understanding and design of hypervalent iodine(III) reagents with versatile Lewis acidity.