Theoretical study of the inhibitive properties of a group of benzimidazoles

Abstract

In this work, a group of benzimidazoles, namely benzimidazole (BIM), 2-hexyl benzimidazole (2-HBIM), and 2-benzyl chloride benzimidazole (2-ClBBIM), have been studied using density functional theory (DFT) at the level of B3LYP with the 6-31G (d) and 6-311G (d, p) base sets in order to elucidate the different inhibition efficiencies and reactive sites of these compounds as corrosion inhibitors. Based on the calculated results, the studied molecules interact with Fe-atoms mainly in their stable pyridine-N protonated forms. It is found that the inhibition efficiencies of the stable protonated molecules involved in this study have a certain relation with some parameters, such as the highest occupied molecular orbital energy (EHOMO) and the global hardness (η). The results indicate that the C (7) atoms, as the reactive sites, receive electrons from Fe-atoms, benzene ring denote electrons to vacant orbital of Fe-atoms. Additionally, Fukui indices and the orbital analyses suggest that 2-ClBBIM has the highest reaction activity among the three molecules, the efficiency order of three inhibitors is found to be 2-ClBBIM > 2-HBIM > BIM, which accords with experimental results. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010