Monitoring Ligand Substitution in (Catalytically Active) Metal Complexes with Bodipy-Tagged Diimines and NHC Ligands

The reaction of 2,6-dimethyl-4-(Bodipy-8-yl)aniline with 1,4-dioxane-2,3-diol provides the respective diimine 3, followed by ring closure with paraformaldehyde, resulting in the imidazolium salt 4·HCl containing two fluorophores. The NHC metal complexes ([IrCl(cod)(4)], [Ir(cod)(4)(py)]OTf, [IrCl(CO)2(4)], [PdCl(allyl)(4)], [PdCl2(Clpy)(4)], [AuCl(4)], and [NiCl(Cp)(4)]) were prepared. The complexes with (Au, Pd) are fluorescent. Weakly fluorescent complexes with Ir undergo fluorogenic reactions with CO and H2. The oxidative addition of H2 to [Ir(cod)(4)]OTf leads to a fluorescence gain of 8.2 and is suitable for the detection of hydrogen. Following activation of the diimine complex [PdCl(CH3)(3)] with NaBArF, the formed [Pd(CH3)(3)]BArF is a competent ethene polymerization catalyst. The addition of (pyridine, CH3CN, CO) or olefins (ethene, 1-hexene, styrene) to the activated complex results in a pronounced increase in the fluorescence because of metal–ligand interactions and the modulation of photoinduce...