Determination of Stereoelectronic Properties of NHC Ligands <i>via</i> Ion Pairing and Fluorescence Spectroscopy

We present an experimental method, which provides information on the steric and electronic properties of ligands in metal complexes. This approach is based equilibrium ion-pairing a cationic [(NHC)Ir(cod)]+ fluorescent bodipy-sulfonate (bdpSO3?). The close ion-pair [(NHC)Ir(bdpSO3)(cod)] toluene solution weakly fluorescent, but dissociates into solvent-separated ion pairs upon exposure to slightly more polar solvents. spatial separation leads very pronounced increase fluorescence. distinct ions depends polarity solvent, importantly also stereoelectronic NHC ligand. 26 different with varying were probed 1,2-dichloroethane solvent. examined via established descriptors (redox potential ?(CO)). systematic variation donation enables deconvolution contributions respective