Phase Diagrams and Solvate Structures of Binary Mixtures of Glymes and Na Salts

Abstract

We prepared a series of binary mixtures composed of selected Na salts and glymes (tetraglyme, G4, and pentaglyme, G5) with different salt concentrations and anionic species ([X](-): [N(SO2CF3)2](-) = [TFSA](-), [N(SO2F)2](-) = [FSA](-), ClO4(-), PF6(-)) and studied the effects of concentration, anionic structure, and glyme chain length on their phase diagrams and solvate structures. The phase diagrams clearly illustrate that all the mixtures form 1:1 complexes, [Na(G4 or G5)1][X]. The thermal stability of the equimolar mixtures was drastically improved in comparison with those of diluted systems, indicating that all the glyme molecules coordinate to Na(+) cations to form equimolar complexes. Single-crystal X-ray crystallography revealed that [Na(G5)1][X] forms characteristic solvate structures in the crystalline state irrespective of the paired anion species. A comparison of the solvate structures of the glyme-Na complexes with those of the glyme-Li complexes suggests that the ionic radii of the coordinated alkali-metal cations have substantial effects on the resulting solvate structures. The Raman bands of the complex cations were assigned by quantum chemical calculations. Concentration dependencies of cationic and anionic Raman spectra show good agreement with the corresponding phase diagrams. In addition, the Raman spectra of the 1:1 complexes strongly suggest that the glymes coordinate to Na(+) cation in the same way in both liquid and crystalline states. However, the aggregated structure in the crystalline state is broken by melting, which is accompanied by a change in the anion coordination.

Room Temperature Magnesium Electrodeposition from Glyme-Coordinated Ammonium Amide Electrolytes

“…In the case of free ethers, which are not coordinated by alkaline metal cations, the Raman band is observed at around 855 cm -1 . 33 Therefore, the Raman band at 852 cm -1 is assignable to free G4, which is seen both in pure G4 and in G4 solution with Mg 2+ :G4 = 1:8 by mole. The spectra for the IL/G4 mixture with Mg 2+ :IL:G4 = 1:7:8 by mole can be viewed as a combination of the spectrum for Mg/G4 and that for Mg/IL.…”

Redox Active Glyme-Li Salt Solvate Ionic Liquids Based on Tetrabromoferrate(III)

“…[8][9][10] Of particular interest are the stoichiometric mixtures of glymemetal salts because they often form a low-melting complex with long-lived complex cation through the chelate effect. 11,12 Many glyme-metal salt complexes have been studied, ranging from alkali metal salts (Li, 13 Na, 14 and K 15 ) to alkali earth metal salts (Mg 16 and Ca 17 ). However, most of the complexes yielding solvate ILs comprise bis(trifluoromethensulfonyl) amide (TFSA) salts owing to their good thermal and electrochemical stabilities, their ability to lower the melting point, and weakly coordinating property that ensures strong glyme-metal ion interactions.…”

Pentaglyme–K salt binary mixtures: phase behavior, solvate structures, and physicochemical properties

“…[25][26][27][28][29][30] Theoretical calculations of equimolar glyme-alkali metal salts have been performed to obtain stable solvate structures. 21,37 However, the border for the K-glyme system is still unambiguous. 33,34 The first use of glyme-Li solvate ILs was as an alternative electrolyte for Li-secondary batteries.…”