Synthesis and Structural Investigation of Some Transition Metals Complexes of Benzimidazolium Bromide

Abstract

The present work involves the synthesis of novel imidazolium salts of bromide in step-wise reactions which are started from preparation of 2,4-dimorpholine-6-(1H-benzimidazole-1-yl)-1,3,5-triazine (1) in potassium hydroxide and DMF solvent followed by substitution reactions with n-butyl bromide and n-octyl bromide to afford the new ligands names L1 = 1-(2,4-dimorpholino-1,3,5-triazine-2-yl)-3-butyl-1H-benzimidazol-3-ium bromide and L2 = 1-(2,4-dimorpholino-1,3,5-triazine-2-yl)-3-octyl-1Hbenimidazol-3-ium bromide. The new ligands were recrystallized from hot chloroform and the following of reactions completion were carried out by thin layer chromatography (TLC). The formula and structures of the two salts of benzimidazolium bromide were confirmed on the basis of measurements of (CHN) elemental analyses, FT-IR, NMR and EIMS spectroscopy. Furthermore the manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes were synthesized from the direct reactions of their hydrated metal salts in methanol with the solutions of the ligands in chloroform in 1:1 mole ratio and the analytical data of atomic absorption spectroscopy and elemental analyses revealed the proposed formula of the solid metal complexes. The data obtained from FT-IR, UV-Visible spectra, molar conductivity and magnetic susceptibility measurements confirmed the octahedral environment around cobalt(II) ion in [CoL(H2O)2Cl2] and the tetrahedral geometry was adopted for manganese(II) and zinc(II) ions. However the square-planner structure was expected for the copper(II) and nickel(II) complexes in [MLCl2], M = Ni(II) and Cu(II) ions and L = L1 and L2 ligands. As well as the suitable and favourable active sites in the two ligands L1 and L2 were the two nitrogen atoms of morpholine rings which has been observed from FT-IR spectra and the kinetic stability of five-member ring up on chelation with the metal ions supported the conclusion of the symmetry.