Conceptual density functional theory (CDFT) provides valuable insights about the ligand effect on the stability, reactivity of imidazolium and NHC systems. The pKa of imidazolium can predict the suitable base used for the generation of NHC from imidazolium system.

Abstract

Imidazolium and its different N-substituted derivatives are considered in this study to investigate their stability, reactivity, and acidity. Different aliphatic and aromatic ligands have been introduced in imidazolium to see their effect. It has been observed that the acidity of imidazolium systems increases with ligands having higher electron-withdrawing nature. The studied systems are found to be weak acids, and weak bases can generate the corresponding carbene systems. The stability, reactivity, and aromaticity of all the systems are analyzed by using conceptual density functional theory (CDFT)-based reactivity descriptors. Nucleus-independent chemical shift (NICS) values lend additional support for the aromatic behavior of the studied molecules.