Inhibitory Effect of three benzothiazole derivatives (1, 3-benzothiazol-2-amine (BTA), 6-methyl-1, 3-benzothiazol-2-amine (MBTA) and 2-amino-1, 3-benzothiazole-6-thiol (TBTA)) on corrosion of carbon steel has been studied using density functional theory (DFT) method in gas and aqueous phases. Quantum chemical parameters such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), hardness (η), polarizability (α), surface area and total negative charges on atoms (TNC) have been calculated at the B3LYP level of theory with 6-311++G** basis set. The Mulliken charges of the molecules were
also computed and Atoms-in-Molecule (AIM) method suggested the Fe-inhibitor interactions in these compounds are partially covalent and partially electrostatic. In good agreement with the experimental data, theoretical results showed the order of inhibitory efficiency is TBTA > MBTA > BTA.
