Solvation Structure of Li+ in Methanol and 2-Propanol Solutions Studied by ATR-IR and Neutron Diffraction with 6Li/7Li Isotopic Substitution Methods.
J Phys Chem B
; 123(23): 4967-4975, 2019 Jun 13.
Article
em En
| MEDLINE
| ID: mdl-31094512
ABSTRACT
Neutron diffraction measurements have been carried out on 10 mol % LiTFSA (TFSA bis(trifluoromethylsulfonil)amide) solutions in methanol- d4 and 2-propanol- d8 to obtain information on the solvation structure of Li+. The detailed coordination structure of solvent molecules within the first solvation shell of Li+ was determined through the least-squares fitting analysis of the difference function between normalized scattering cross sections observed for 6Li/7Li isotopically substituted sample solutions. The nearest-neighbor Li+···O distance and coordination number determined for the 10 mol % LiTFSA-methanol- d4 solution are rLiO = 1.98 ± 0.02 Å and nLiO = 3.8 ± 0.6, respectively. In the 2-propanol- d8 solution, it has been revealed that 2-propanol- d8 molecules within the first solvation shell of Li+ take at least two different coordination geometries with the intermolecular nearest-neighbor Li+···O distance of rLiO = 1.93 ± 0.04 Å. The Li+···O coordination number, nLiO = 3.3 ± 0.3, is determined. Ion-pair formation in the LiTFSA-methanol and LiTFSA-2-propanol solutions has been investigated by the attenuated total reflection infrared spectroscopic method. Mole fractions of free, Li+-bound, and aggregated TFSA- are derived from the peak deconvolution analysis of vibrational bands observed for TFSA-.
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01-internacional
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MEDLINE
Idioma:
En
Revista:
J Phys Chem B
Ano de publicação:
2019
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Article