In general, the stability of neutral complexes with dative bonds increases as the polarity of the solvent increases. This is based on the fact that the dipole moment of the complex increases as the charge transferred from the donor to the acceptor increases. As a result, the solvation energy of the complex becomes greater than that of subsystems, causing an increase in the stabilization energy with increasing solvent polarity. Our research confirms this assumption, but only when the charge transfer is sufficiently large. If it is below a certain threshold, the increase in the complex's dipole moment is insufficient to result in a higher solvation energy than subsystems. Thus, the magnitude of the charge transfer in the Lewis electron-pair system determines the stability trends of dative bonds with varying solvent polarity. We used molecular dynamics (MD) simulations based on an explicit solvent model, which is considered more reliable, to verify the results obtained with a continuous solvent model.

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences v v i Flemingovo nám 2 Prague 6 16000 Czech Republic

IT4Innovations VŠB Technical University of Ostrava 17 listopadu 2172 15 Ostrava Poruba 70800 Czech Republic

Regional Centre of Advanced Technologies and Materials Czech Advanced Technology and Research Institute Palacký University Olomouc Křížkovského 511 8 Olomouc 77900 Czech Republic

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Striking Impact of Solvent Polarity on the Strength of Hydrogen-Bonded Complexes: A Nexus Between Theory and Experiment