PM3 and DFTQuantum MechanicalCalculations of Two New N-Benzyl-5-BromoIsatin Derivatives as Corrosion Inhibitors

ABSTRACT Theoretically two new derivatives of N-benzyl-5-bromoisatinnamelyN-benzyl-5-bromo-3-[(imine aceto) urea]-2-oxo indole (5BIO) and N-benzyl-5-bromo-3-[(imine aceto) thiourea]-2-oxo indole (5BIS) have been investigated as acorrosion inhibitors for carbon steel surface in three media(vacuum, DMSO, and H2O) using quantum mechanics calculations of the approximate semiempiricaltheory PM3 and Density Functional Theory DFT of (B3LYP) with a 6-311++G (2d,2p)byusing Gaussian-09 program.The calculations ofphysical properties and quantum chemical parameters correlated to the inhibition efficiency all are studied and discussed at the equilibrium geometryat the three media. The results indicated that the twoN-benzyl-5-bromoisatin derivatives could adsorb on the carbon steel surface firmly through the heteroatoms and through the3-[(imine aceto) urea] for (5BIO)and 3-[(imine aceto) thiourea] for(5BIS), showing that the two inhibitors have excellent corrosioninhibition performance, and (5BIS) is a better corrosion inhibitor than (5BIO).