Density Functional Theory Investigations for the adsorption of some Oxadiazole Derivatives on Mild Steel.

Two oxadiazole derivatives namely 2,5-bis(4-methylphenyl)-1,3,4-oxadiazole (Inh-1) and 2,5-bis(4-methoxyphenyl)-1,3,4-oxadiazole (Inh-II) were investigated as corrosion inhibitors for mild steel using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Quantum chemical parameters most relevant to their potential action as corrosion inhibitors such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy gap(ΔE), hardness (η), Softness(S), dipole moment(μ), electron affinity(A), ionization potential(I), the absolute electronegativity (χ), the fraction of electron transferred (ΔN), electrophilicity index(ω) and the back-donation(ΔE Back-donation) have been calculated and discussed. The local reactivity has been analysed through the Fukui and condensed softness indices inorder to predict both the reactive centres and to know the possible sites of nucleophilic and electrophilic attacks. The theoretical conclusions were found to be consistent with the experimental data reported. [ABSTRACT FROM AUTHOR]