On the consistent use of electrophilicity index and HSAB-based electron transfer and its associated change of energy parameters

The electrophilicity index is often used in an inconsistent manner with other HSAB (Hard and Soft Acids and Bases) based parameters that depend on absolute hardness, such as, electron transfer (ΔN) and its associated change of energy (ΔE). We further comment on the use of ΔN parameter in the quantum chemical studies of corrosion inhibitors, where this parameter is used to discuss the interaction between an inhibitor molecule and metal surface. It is argued that the work function of metal surface is an appropriate measure of its electronegativity and should be used together with its vanishing absolute hardness to estimate the ΔN.