Metal-responsive activation of C–O and C–C bonds of an aromatic vicinal diol in hydrothermal conditions: synthesis, structure, mechanism and magnetic properties

Abstract

The selective in situ reactions of 1,2-di(1H-benzimidazol-2-yl)ethane-1,2-diol (TDB) in the presence of 3d transition-metal ions under hydrothermal conditions were investigated. The research demonstrated that divalent Fe, Co, and Ni salts are apt to cause the intramolecular dehydration of TDB, then form pentanuclear [M₅(H₂L)₆]⁴⁺ clusters, and Cu cations tend to activate specific C–C bonds, then give rise to benzimidazole derivatives and the corresponding copper(I/II) complexes. The results illuminate that reaction temperature and pressure are necessary conditions for molecular rearrangement and the radii and valence state of metal ions are key factors in the metal-responsive decomposition of TDB. Based on the results, the corresponding mechanism is proposed. Moreover, the synthesis, crystal structure, thermal stability and magnetism of related complexes are investigated.