The impact of the solvent dielectric constant on A←NH3 dative bond depends on the nature of the Lewis electron-pair systems

Abstract

The present work aims to determine to what extent the value of the dielectric constant of the solvent can influence the dative bond in Lewis electron pair bonding systems. For this purpose, two different systems, namely H3B <- NH3 and {Zn <-(NH3)}(2+), were studied in selected solvents with significantly different dielectric constants. Based on the results from state-of-the-art computational methods using DFT, constrained DFT, energy decomposition analyses, solvent accessible surface area, and charge transfer calculations, we found that the stability of the neutral H3B <- NH3 system increases with increasing solvent polarity. In contrast, the opposite trend is observed for the positively charged {Zn <-(NH3)}(2+). The observed changes are attributed to different charge redistributions in neutral and charged complexes, which are reflected by a different response to the solvent and are quantified by changes in solvation energies.