In present investigation, we have designed several novel corrosion inhibition compounds using diazenyl as central core while pyrazole-5-one and substituted phenyl as lateral moieties (hereafter will be called diazenyl derivatives). The ground state geometries of diazenyl derivatives have been optimized by using density functional theory (DFT) methods with three different basis sets i.e. 6-31G*, 6-311G** and 6-311++G**. The inhibition efficiency of different diazenyl derivatives has been calculated to determine the relationship between their molecular structures and inhibition activity. The calculated efficiencies have also compared with some standard organic inhibitors. Several quantum chemical parameters, specifically, E_HOMO (highest occupied molecular orbital energy), E_LUMO (lowest unoccupied molecular orbital energy), the energy difference between E_HOMO and E_LUMO (Δ E), dipole moment (μ), electron affinity (EA), ionization potential (IP), the absolute electronegativity (χ), absolute hardness (η), softness (Σ), Mulliken charges, and the fraction of electrons (ΔN) transfer from inhibitors to iron were calculated and correlated. We have also shed light on the polarizabilty, static first hyperpolarizability (β_tot) and its components.