Solvent effect on stabilization energy: An approach based on density functional reactivity theory

Abstract

In the present article a formalism and the corresponding computational method is developed to take care of the variation of stabilization energy with solvent polarity in the process of adduct formation. For this purpose, a simple but physically insightful definition of “net desolvation energy” is proposed keeping in mind the sequence of events taking place in the process of adduct formation in a solvent. The approach used here is based on density functional reactivity theory (DFRT) and the representative samples chosen are adduct formation between (a) methyltrioxorhenium (MTO) and pyridine and (b) (azidomethyl)benzene and methylpropiolate. The generated data in case (a) is correlated with already known experimental parameter that is, formation constant (Kf). The observed trends claim that with the increase in solvent polarity interaction (or stabilization) energy becomes less negative which means that on increasing the solvent polarity the chances of adduct formation are less. This is further supported by calculating hardness values of adducts in different solvents which goes on decreasing with the increase in solvent polarity. Here, the computed data show that on increasing the polarity (i.e., dielectric constant) of the solvent, the “net desolvation energy” increases. Finally, when “net desolvation energy” is added to the stabilization energy obtained from DFRT the predicted trends are achieved.