Intramolecular hydroxylation of a tetrabenzimidazole-based dicopper complex

Monometallic copper complexes were obtained with the bis(benzimidazole) ligand BBM, which served as precursor for the tetra(benzimidazole) ligand TBP. The latter afforded the dicopper complex [(TBP2Cu2)OTf4] that undergoes ligand hydroxylation in air resulting in the mixed-valence [(TBPO2Cu2)OTf]. [Display omitted] •Bis(benzimidazole) building blocks prepared in good yield.•Tetra(benzimidazole) binucleating ligand is reported.•Mono- and dicopper complexes obtained with the benzimidazole-based ligands.•Dicopper complex intramolecularly hydroxylates benzylic ligand positions. The synthesis of bis(N-methylbenzimidazol-2-yl)methane serves as the entry point for the preparation of a tetrabenzimidazole-based binucleating ligand. A cupric complex of the former compound was prepared to compare its properties to those of the dicopper complexes of the tetrabenzimidazole derivative. In the latter case, the reaction of the binucleating ligand with cupric trifluoromethylsulfonate in air results in intramolecular CH activation with concomitant hydroxylation, presumably by an in situ formed copper-oxygen reactive intermediate. This reactivity highlights the relevance of benzimidazole-based scaffolds in biologically inspired copper-oxygen systems.