Steric Properties of N‐Heterocyclic Carbenes affect the Performance of Electronic Probes

Abstract Electronic probes of ligands, particularly carbenes, are widely used in assessing electronic properties; the results inform the selection of a ligand for a given application. As such, it is important to ensure the data obtained is reliable and unaffected by other factors, such as the steric bulk of the ligand. The effects of such steric factors on two commonly used electronic probes (based on palladium and selenium) are investigated here, with the selenium adduct found to be particularly sensitive. It is hoped that this serves as a cautionary tale to always critically evaluate what a probe is measuring.