Solvation of anions in acetonitrile solutions: FTIR and quantum chemical study for Br−, ClO4−, AsF6−, and CF3SO3−

Ion-Pairing Dynamics Revealed by Kinetically Resolved In Situ FTIR Spectroelectrochemistry during Lithium-Ion Storage

“…There is still a debate in the literature as to the nature of peaks 2 and 4, owing either to the formation of isotopomers or a change in solvation number. 40,53 To simplify the analysis, we will focus on the primary peaks for paired (Paired ClO 4 − , peak 1, 1134 cm −1 ) and unpaired perchlorate (Unpaired ClO 4 − , peak 3, 1102 cm −1 ). These will serve as vibrational reporters for the association and dissociation of ion pairs.…”

“…One might anticipate that electron accumulation associated with extracting Li + from contact ion pairs may proceed prior to that associated with extracting Li + from within their full solvation shell due to the thermodynamic comparison of the solvation energy of Li-ACN 4 (−295 kJ/mol) and Li-ClO 4 ion-association energy (−9.1 kJ/mol). 53,55 Global target analysis was used to successfully fit the two spectral regions of interest (nitrile and perchlorate) to the same sequential model. The resulting Species Associated Difference Spectra (SADS) for each region (Figure 5a,b) elucidate the vibrational signatures that are either enriched (positive peak) or depleted (negative peak) for each kinetically distinct regime.…”

“…Of these five bands shown in Figure b, three (1, 2, and 5) are associated with CIPs formed by the direct interaction between Li + and ClO 4 – and two are associated with free, unpaired perchlorate (3 and 4). There is still a debate in the literature as to the nature of peaks 2 and 4, owing either to the formation of isotopomers or a change in solvation number. , To simplify the analysis, we will focus on the primary peaks for paired ( Paired ClO 4 – , peak 1, 1134 cm –1 ) and unpaired perchlorate ( Unpaired ClO 4 – , peak 3, 1102 cm –1 ). These will serve as vibrational reporters for the association and dissociation of ion pairs.…”

Constrained Molecular Dynamic Simulation of the Potential Mean Force of Lithium Bromide Ion Pairs in Acetonitrile

“…This value may be attributed to the deficiency in the interaction potentials used. Nevertheless, other studies indicate that the solvation shell of the Br-anion can have a maximum number of molecules of acetonitrile bigger than 10 [9]. It should also be pointed out that in aqueous solutions coordination numbers increase when the concentration decrease [26].…”

“…When acetonitrile is utilized as the solvent, solvation numbers in the range of 1-9 are discovered in the literature for this anion. Furthermore, the solvent molecules' molecular organization is not well understood [9][10][11].…”