Facile N–N coupling and copper (II) promoted cleavage of N,N′-linked N-methylbenzimidazole

Together with the facile and high yielding formation of N,N′-linked NHC ligand, the complexation of N-methylbenzimidazole (1a), N-methylbenzimdiazolium chloride (4a) and N,N′-linked NHC ligand, 3,3-dimethyl-1,1-bibenzimidazolium dichloride (2a), with CuO or CuCl2 give a dichloro-bridged binuclear copper(II) species (Ia), as characterized by IR spectroscopy and X-ray.