Structural, theoretical and corrosion inhibition studies on some transition metal complexes derived from heterocyclic system

Publication date: 5 June 2017
Source:Journal of Molecular Structure, Volume 1137
Author(s): Shraddha Rani Gupta, Punita Mourya, M.M. Singh, Vinod P. Singh
A Schiff base, (E)-N′-((1H-indol-3-yl)methylene)-2-aminobenzohydrazide (Iabh) and its Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized. These compounds have been characterized by different physico-chemical and spectroscopic tools (UV–Vis, IR, NMR and ESI-Mass). The molecular structure of Iabh is determined by single crystal X-ray diffraction technique. The ligand Iabh displays E-configuration about the >CN− bond. The structure of ligand is stabilized by intra-molecular H-bonding. In all the metal complexes the ligand coordinates through azomethine-N and carbonyl-O resulting a distorted octahedral geometry for Mn(II), Co(II) and Cu(II) complexes in which chloride ions occupy axial positions. Ni(II) and Zn(II) complexes, however, form 4-coordinate distorted square planer and tetrahedral geometry around metal ion, respectively. The structures of the complexes have been satisfactorily modeled by calculations based on density functional theory (DFT) and time dependent-DFT (TD-DFT). The corrosion inhibition study of the compounds have been performed against mild steel in 0.5 M H2SO4 solution at 298 K by using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). They show appreciable corrosion inhibition property.

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