Investigation of Newly Pyridazine Derivatives as Corrosion Inhibitors in Molar hydrochloric Acid. Part III: Computational Calculations

摘要

Quantum chemical calculations, based on DFT methods at B3LYP/6-31G** level of theory, wereperformed, by means of the GAUSSIAN 03 set of programs, on four recognized pyridazinecompounds as corrosion inhibitors in acidic media. The objective of this work is to attempt to findrelationships between their molecular and electronic structures and inhibition efficiency. The structuralparameters, such as the frontier molecular orbital energies (EHOMO and ELUMO), gap of energy , thecharge distribution, the absolute hardness and softens the fraction of electrons 凬 transferredfrom pyridazine molecules to iron as well as electronic parameters such as Mulliken atomicpopulations and Fukui indices were calculated and discussed. The behaviour of these organicmolecules in the presence of solvents, among them water, has facilitated the understanding of thecorrosion inhibition process. Significant correlations were obtained between the calculated descriptorsand experimental outcomes. The study clearly show that the substitution of an oxygen atom by sulphurone was very beneficial towards corrosion inhibition of mild steel in 1 M HCl.