Combining experimental and theoretical vibrational spectroscopy to study magnesium aluminum chloride complex electrolytes

Measurements of the Far-IR and Raman spectra of 1:1 MACC-ether electrolytes were carried out. [(mu-Cl)(2)Mg-2](2+) is the major dimer in DME solution and the bands at 250 and 222 cm(-1) may be used as markers in the respective IR and Raman spectra. On the other hand, [MgCl](+) stands out in the THF-based electrolyte, where an IR band at 286 cm(-1) is here reported for the first time in the literature and may be employed as sensor. The [(mu-Cl)(3)Mg-2](+) dimer, which is usually formed at the 2:1 MACC-THF electrolyte and deemed the electrochemically active species on the electrode, is also identified at the 1:1 ratio. AIMD-simulated IR spectra of the dimer and monomer are in good agreement with the experimental data and were pivotal to characterize the [MgCl(THF)(5)](+) complex. QC calculations helped assign a few bands in the Raman spectra and Gibbs free energies explained the preferential formation of Mg species in each medium. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Measurements of the Far-IR and Raman spectra of 1:1 MACC-ether electrolytes were conducted in this study, revealing the major dimers [(mu-Cl)(2)Mg-2](2+) and [MgCl](+). A new IR band was identified in THF-based electrolytes, which may serve as a sensor. Additionally, the [(mu-Cl)(3)Mg-2](+) dimer was found in both 2:1 and 1:1 MACC-THF electrolytes, indicating the presence of electrochemically active species even at a 1:1 ratio.