Extensive theoretical study of corrosion inhibition efficiency of some pyrimidine derivatives on iron and the proposal of new inhibitor

The retarding of metal corrosion due to the effect on economic and safety matters is a challenging research area. The theoretical study could be helpful to understand the mechanism of inhibition and design some new inhibitors. The electronic properties of some pyrimidine derivatives in the gas and aqueous phase were investigated using the m062x/6-311G(3df,3pd) level of theory and the plane wave pseudopotential method and PBE functional were used in the analysis on the Fe(111) surface. The volume and HLG gave the better results for isolated molecule study. Different groups substituted or replaced in thion 2-mercapto pyrimidine (S=Py) structure to enhance its inhibition efficiency. The replacement of Se instead of S revealed the best results in all parameters. The study of inhibitor interaction with the metal surface provides better correlation with the experimental inhibition efficiency and better insight. Keto tautomers represented more efficiency in both gas and solid phase. We predicted that halogenate compounds obey different mechanism to prevent corrosion. Bader analysis indicated that the charge flow occurs from Fe atoms toward inhibitor molecules. As thermodynamic studies confirm that Se=Py is a good inhibitor, the kinetic study of dehydrogenation by CI-NEB method showed lower activation energy for it. So it may be introduced as a new inhibition candidate.