The link between the ionization potential and heat of formation for organic homologous compounds

Based on the relationship between the heat of formation and the change of valence electronic energy in the formation of a compound from its component atoms, and combined with the relationship between the first ionization potential and the average valence electronic energy, the direct link of ionization potential, Ip, with the heat of formation, ΔH⁰_f, was deduced for organic homologous compounds, that is, where N_ve,m is the number of valence electrons in molecule, SVEE_x is the sum of valence electronic energy of isolated atoms forming the molecule, the term expresses the initial‐state effect of the molecule, and the symbol R_m represents its final‐state effect (polarizability effect). The above equation was confirmed by the correlations between the ionization potentials and the heat of formation of alkanes, alkenes, monosubstituted alkanes RY (Y = OH, NH₂, SH, Cl, Br, and I), in which all the expressions have good correlations with correlation coefficients more than 0.9990. With the obtained correlation equations, the ionization potentials of some monosubstituted alkanes were predicted from their experimental heats of formation. The result provides a new insight into the intercorrelation between the ionization potential and the heat of formation for organic homologous compounds. Copyright © 2007 John Wiley & Sons, Ltd.