Transition metal complexes of a benzimidazole ligand containing two heptyl chains: Synthesis, crystal structures, photophysical and thermal properties

In this study, a benzimidazole ligand (L) containing two heptyl chains and its transition metal [Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] complexes were prepared and characterized by spectroscopic and analytical methods. Molecular structures of the complexes [Mn(L)Cl-2], [Co(L)Cl-2], [Cu(L)Cl-2] and [Zn(L) Cl-2] were determined by X-ray diffraction studies. In the structure of the complexes, metal ions are five-coordinate with distorted square pyramidal geometry. X-ray structural data showed the alignment of the heptyl aliphatic chains and the bond angles between the two coordinated chloride angles (Cl-M-Cl) have an effect on the crystal packing of the complex molecules. The ligand-based emission band showed a red-shift in the spectra of [Fe(L)Cl-2] and [Zn( L)Cl-2] complexes. Finally, thermal behaviours of the ligand and its metal complexes were studied under nitrogen atmosphere. The complexes were found to decompose at higher temperatures than that of the ligand. (C) 2019 Elsevier B.V. All rights reserved.