N-[(3-Bromo-2-methylthiophen-5-yl)methylene]-4-methoxyaniline) (5) has been synthesized and used as corrosion inhibitor for zinc metal in 2 M HCl at room temperature by using weight loss measurements. The obtained results showed that (5) is a good inhibitor and its inhibition efficiency (IE %) increased with the increase of inhibitor concentration. The surface coverage was 1.55 at 500 ppm inhibitor concentration; hence the optimum concentration was 500 ppm. Theoretical calculations investigate by studying the relationship between molecular structure and inhibition efficiency using semi-empirical molecular quantum calculations within the PM3 method as implemented in HyperChem package.

A theoretical study of semi-empirical calculation of PM3 level was used to characterize three Tin complexes (R 2 SnL 2) [where (R): (Phenyl), (butyl) and (methyl) and L: (N-tolyl-mmethoxybenzo hydroxamic acid) ]. The comparison of the three complexes that have different (R) had been done on the basis of calculated energies and physical properties of the molecular model systems, such as heat of formation, HOMO-LUMO gap, binding energy, dipole moment, surface area. This present study revealed a clear picture and useful information about the nature of complex stability of the three Tin complexes R 2 SnL 2 .