Electrochemical Generation of Pyrazolyl-Pyridyl N-Heterocyclic Carbene Complexes of Nickel

By methods of cyclic voltammetry and preparative electrolysis, the electrochemical properties of sterically hindered imidazolium salt 3-(6-(1H-pyrazol-1-yl)pyridin-2-yl)-1-(2,6-diisopropylphenyl)-1H-imidazol-3-ium bromide containing the pyrazolyl-pyridyl moiety are studied and the N-heterocyclic carbene complexes of nickel(II) are electrochemically synthesized by the cathodic reduction of this salt in the presence of nickel(II) ions. The monitoring of this preparative electrosynthesis by mass spectrometric measurements demonstrates that these organonickel complexes can contain either one (when a diaphragm cell is used) or two (when the diaphragmless cell contains a soluble nickel anode) N-heterocyclic carbene ligands.