New hydrazine derivatives as corrosion for mild steel in phosphoric acid medium. Part B: Theoretical investigation

Three hydrazine derivatives namely: 1,2-bis(pyrrol-2-ylidenemethyl)hydrazine (hz1); 1,2-bis(thiophen-2-ylidenemethyl)hydrazine (hz2); 1,2-bis(furyl-2-ylidenmethyl)hydrazine (hz3) were investigated as corrosion inhibitors of mild steel in phosphoric acid using experimental and theoretical methods. in this part,quantum chemical calculations based on dft and qsar methods were performed to determine the relationship between the molecular structure of hydrazines and their inhibition efficiencies. the quantum chemical parameters such as the localization of frontier molecular orbitals,ehomo,elumo,energy gap(δe),dipole moment(μ),hardness(η),softness(s),the fractions of electrons transmit(δn),electrophilicity index (ξ) and total energy charge were calculated and used to explicate the electron transfer mechanism between the inhibitor molecules and the steel surface. furthermore,statistical equations were proposed using the multiple-linear and the nonlinear regression analysis.