Quantum-Chemical and Molecular Dynamics Investigations of Magnesium Chloride Complexes in Dimethoxyethane Solutions

Quantum-chemical calculations and classical and ab initio molecular dynamics simulations have been performed to study the Mg²⁺-conducting electrolytes based on Mg(TFSI)₂/MgCl₂ solutions in dimethoxyethane. It has been shown that depending on the TFSI/Cl^- ratio, the Mg₂Cl₂ ²⁺ or Mg₃Cl₄ ²⁺ complexes are preferred as stable ion aggregates. In the initial stages of the ion association process, MgCl⁺, MgCl₂, and Mg₂Cl₃ ⁺ are formed as intermediate species. Calculations of harmonic frequencies and simulations of the IR spectrum of the electrolyte from the ab initio MD trajectories have been used to identify the spectral range of vibrations of ion aggregates found in the modeled electrolyte. The results have been discussed in the context of experimental data.