THE E, C, AND T-INTERPRETATION OF BOND-DISSOCIATION ENERGIES AND ANION NEUTRAL MOLECULE INTERACTIONS

Gas-phase enthalpies for anions bonding to neutral acids and enthalpies of dissociation are incorporated into the E and C model with excellent results. In addition to predicting and interpreting enthalpies, the resulting parameters for anions and radicals provide reactivity scales that can be used to interpret physicochemical properties. Significant chemical insights result from the fit of the data to the ECT model. The predicted HSAB basicity order of the anions is not obtained in the gas phase and is shown to result for displacement reactions in water because the hydrogen bonding of water to the anions levels the strength and the electrostatic contribution to their basicity. The parameters from the bond energy fit follow trends with literature estimates of ionic and covalent character. The partial charges in molecules from ab initio calculations are reproduced by trends in the bond energy parameters. It is concluded that no scale of electronegativity, substituted into a difference function, can correlate bond energies to their known accuracy. This new model concludes that polarity is a consequence of the product of the transmittance of the atom at the positive end of the dipole and the receptance of the atom forming the negative end. The electron transfer is further driven by the stabilization of the bond from ionic interactions. One-parameter physicochemical correlations with electronegativity will only be successful under a very limited set of specified conditions. No improvement in the electronegativity parameters will change these conclusions. Differences in electronegativities for atoms (modified herein with more recent data, and those calculated for radicals as described) should mainly be used in the qualitative way that Pauling intended to predict the ionicity of bonds.