Determination of Kamlet-Taft parameters for selected solvate ionic liquids

Abstract

The normalised polarity E and Kamlet-Taft parameters of recently described solvate ionic liquids, composed of lithium bis(trifluoromethyl)sulfonimide (LiTFSI) in tri- () or tetraglyme () have been determined and compared to the parent glyme ( and ). We show that these solvate ionic liquids have a high polarity (, (E) = 1.03; , (E) = 1.03) and display very high electron pair accepting characteristics (, α = 1.32; , α = 1.35). Molecular dynamics simulations suggest that the chelated lithium cation is responsible for this observation. The relatively small hydrogen bond acceptor (β) values for these systems (, β = 0.41; , β = 0.37) are thought to be due primarily to the TFSI anion, which is supplemented slightly by the glyme oxygen atom. In addition, these solvate ionic liquids are found to have a high polarisability (, π* = 0.94; , π* = 0.90).