Synthesis and characterization of Pd/NHCF complexes with fluorinated aryl groups
The key problem of the instability of fluorine-containing diazadienes was addressed to perform the efficient synthesis of imidazolium salts containing fluorine substituents in the aryl groups. The subsequent reaction of fluorine-containing imidazolium compounds (NHC F) with palladium salts under simple conditions afforded new Pd/NHCF complexes. Computational and structural studies were performed to assess the effect of fluorine on the Pd–NHC bond and gave insight into the electronic effects in the molecule. The introduction of fluorine substituents into the aryl rings of the NHC ligands leads to a slight decrease in their ?-donor properties. At the same time, there is a slight increase in the ?-acceptor capacity of NHCF. These two effects compensate for each other, so that the Pd–NHC bonding energy remains virtually unchanged. Another observed effect is associated with a slight weakening of the trans influence of the NHCF ligands, which is expressed in the strengthening of the Pd–Solv bond in (NHC)Pd(Solv) complexes. For the first time, a series of novel Pd/NHCF complexes were synthesized via a straightforward approach from fluorine-containing anilines.
Reference: Dalton Trans., 2022,51, 9843-9856
