Syntheses, structures, and properties of transition metal complexes with 2-(n-pyridyl)benzimidazole (n=2, 3, and 4)

Article abstract of DOI:10.1080/00958972.2011.635375

Three pyridylbenzimidazoles (2-PBIM, 3-PBIM, and 4-PBIM) have been prepared (2-PBIM: 2-(2-pyridyl)-benzimidazole, 3-PBIM: 2-(3-pyridyl)-benzimidazole, 4-PBIM: 2-(4-pyridyl)-benzimidazole). Reactions of several transition metals (Cd²⁺, Cu²⁺, Fe²⁺) with the three ligands gave four new coordination complexes, [(Cd)₂(2-PBIM)₂(CH ₃COO)₄] (1), [Cu(3-PBIM)₂ (CH ₃COO)₂] · 2H₂O (2), [Cu(4-PBIM) ₂(CH₃COO)₂(H₂O)] · H ₂O (3), and [Fe(4-PBIM)₂ (Cl)₂(H ₂O)₂] (4), respectively. These four complexes have been characterized by X-ray crystallography, IR spectroscopy, and UV absorption spectroscopy. Thermogravimetric properties of 2 and 4 were also measured. X-ray crystallographic studies reveal that these four complexes are very different, although the ligands are similar in structure. The role of hydrogen-bonding and π-π interactions in extending dimensionality of simple complexes has been discussed.