Electronic properties of chelating dicarbene palladium complexes: A combined electrochemical, NMR and XPS investigation

A series of N-heterocyclic dicarbene palladium(II) complexes has been characterised combining different techniques (cyclic voltammetry, XPS and 13C NMR spectroscopy), in order to evaluate the influence of the dicarbene ligand on the electronic properties of the metal centre. The data obtained with the three techniques give relevant information, cyclic voltammetry appearing the most useful approach. In addition, the observed variations of the physico-chemical properties of the complexes confirm the possibility of finely tuning the electronic properties of the palladium(II) centre by changing the characteristics of the dicarbene ligand (wingtip substituents, bridging group between the carbene units, type of heterocyclic ring).