Iron-ligand complex, an efficient inhibitor of steel corrosion in hydrochloric acid media

•The FeSO4(Hdpz) complex exhibited excellent inhibition efficiency against mild steel corrosion in 1 M HCl.•Polarization curves shows that the complex FeSO4(Hdpz) basically functions as a mixed inhibitor.•The quantum approach and monte carlo simulation was confirmed the reactivity of the studied compound towards the corrosion process.•The gibbs free energy values for the adsorption process indicated that physical and chemical adsorption mechanisms were involved.