Relaxation Kinetics and Infrared Spectra of the Complexation of Lithium Ion by Triethylene Glycol and by Tetraethylene Glycol in Acetonitrile

Article abstract of DOI:10.1021/j100193a040

Ultrasonic absorption relaxation spectra are reported covering the frequency range ca. 1-500 MHz for the complexation of LiClO4 by the open-chain polyethers triethylene glycol (EG3) and tetraethylene glycol (EG4) in acetonitrile at 25 deg C and at a molar ratio R = / or R = / = 1.The ultrasonic spectra can be described by the sum of two Debye relaxation processes which were interpreted according to the Eigen-Winkler mechanism Li⁺ + EG <*> Li⁺...EG <*> Li⁺EG <*> (Li⁺EG) (where EG denotes either EG3 or EG4), giving the rateconstants k₁, k_-1, k₂, and k_-2.The first step is taken to be a preequilibrium step for which K₀ is calculated from classical statistical theory.The rate constants are compared with those of the corresponding process involving triglyme and poly(ethylene oxide) (PEO) previously reported.Infrared data for the 3800-3200-cm^-1 region show a shift of 70 cm^-1 to lower energy, indicating a strong interaction between the ethanolic oxygen of EG3 and the Li⁺ ion.