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.

Graphical abstractThe easy and high yielding, yet non-trivial formation of N,N′-linked NHC ligands, which is an uncommon phenomenon during the desired synthetic NHC reaction protocols, specifically, the N,N′-linked NHCs are 3,3-dimethyl-1,1-bibenzimidazolium dichloride (2a) and 3,3-dibenzyl-1,1-bibenzimidazolium dichloride (2b), were formed. Furthermore, the compound (2a) was homolytically cleaved by CuO or CuCl2 under NaH to furnish the binuclear species [(N-MeBenzimz)2Cu(μ-Cl)]2Cl2 (Ia) characterized by single crystal X-ray crystallography.Figure optionsDownload full-size imageDownload as PowerPoint slide