Synthesis and Crystal Structures of Co(II) Complexes Derived From Two Unsymmetrical Bis-Heterocyclic Ligands With Benzimidazole Moiety

Treatment of two kinds of unsymmetrical bis-heterocyclic ligands bearing benzimidazole moiety, 2-[2-(1,2,4-triazole-1-yl)ethyl]-1H-benzimidazole (L1) and 2-[2-(1,2,3-benzotriazole-1-yl)ethyl]-1H-benzimidazole (L2), with Co(II) chloride, resulted in two new complexes, [Co3(L2)4Cl6]·2H2O (1) and [Co(L1)Cl2]2 (2), with different aggregating patterns. Two complexes were characterized by single-crystal X-ray determinations. In the solid state, L1 assumes an anti conformation in compound 1, whereas L2 exists as a gauche conformer in compound 2. Complex 1 reveals a 1-D double-stranded chain structure consisting of both octahedrally and tetrahedrally coordinated Co(II) ions. Complex 2 is a mononuclear tetrahedral Co(II) species, which was hydrogen bonded with each other to give a 1-D linear chain.