Sodium β-Diketonate Glyme Adducts as Precursors for Fluoride Phases: Synthesis, Characterization and Functional Validation

Abstract

Very few sodium complexes are available as precursors for the syntheses of sodium-based nanostructured materials. Herein, the diglyme, triglyme, and tetraglyme (CH3O(CH2CH2O)nCH3, n = 2–4) adducts of sodium hexafluoroacetylacetonate were synthesized in a single-step reaction and characterized by IR spectroscopy, 1H, and 13C NMR. Single-crystal X-ray diffraction studies provide evidence of the formation of the ionic oligomeric structure [Na4(hfa)6]2−•2[Na(diglyme2]+ when the diglyme is coordinated, while a mononuclear seven-coordinated complex Na(hfa)•tetraglyme is formed with the tetraglyme. Reaction with the monoglyme (CH3OCH2CH2OCH3) does not occur, and the unadducted polymeric structure [Na(hfa)]n forms, while the triglyme gives rise to a liquid adduct, Na(hfa)•triglyme•H2O. Thermal analysis data reveal great potentialities for their applications as precursors in metalorganic chemical vapor deposition (MOCVD) and sol-gel processes. As a proof-of-concept, the Na(hfa)•tetraglyme adduct was successfully applied to both the low-pressure MOCVD and the sol-gel/spin-coating synthesis of NaF films.

Highly stable CsPbBr3 perovskite phases from new lead β-diketonate glyme adducts

“…The NMR spectra of “Pb(hfa) 2 ·glyme” complexes 1–4 have been recorded in CD 3 CN; the complete signal attribution is reported in Table 2. The spectra clearly show the signal of both the polyether moieties and the hfa anions, as previously reported for similar complexes; 61,64 neither the 1 H nor the 13 C spectra show evidence of tautomeric equilibria for the hfa moieties: the anionic enolate form is the only species observed in a solution for all the adducts.…”

“…[57][58][59][60][61] Lead β-diketonates are used as precursors in vapor phase processes, such as the case of Pb(tmhd) 2 [(H-tmhd = 2,2,6,6-tetramethyl-3,5-heptanedione)], Pb(acac) 2 , [(H-acac = 2,4-pentanedione)], and their derivatives. 56,62 It has been demonstrated that glymes, through oxygen-ion complexation, are very important for the stabilization of alkaline, 61,63,64 alkaline-earth 65,66 and rare-earth 67 metals. The presence of such a class of multidentate ligands, in fact, permits also to fine-tune the properties of the final metal adducts in terms of thermal stability, moisture-and air-sensitivity, solubility, and volatility.…”

“…It has been demonstrated that glymes, through oxygen-ion complexation, are very important for the stabilization of alkaline, 61,63,64 alkaline-earth 65,66 and rare-earth 67 metals. The presence of such a class of multidentate ligands, in fact, permits also to fine-tune the properties of the final metal adducts in terms of thermal stability, moisture- and air-sensitivity, solubility, and volatility.…”

Probing the Electrode–Electrolyte Interface of Sodium/Glyme-Based Battery Electrolytes

“…Chelation replaces multiple monodentate ligands (such as carbonates in conventional battery electrolytes) coordinating with the alkali metal ion with a single moiety (in this case, glyme), which is entropically favored. This translates into higher coordination numbers compared to typical carbonate solvents. , Previous studies have shown that glyme-based solvents with sodium salts have two glyme molecules complexing with the cation in the case of diglyme and triglyme systems, and one to two distinct glyme molecules in the solvation shells of tetraglyme systems . The chelating effect is particularly pronounced in longer glymes resulting in increased oxidative stability. ,, Electronic structure calculations show that the interactions between metal cations and the oxygen atoms of glymes lead to a notable reduction in the highest occupied molecular orbital (HOMO) energy levels of glymes. , Furthermore, glymes also have the excellent property of cointercalation with Na ions into graphite, directly participating in the sodium ion storage process. − Regarding electrode materials, carbon-based substances like hard carbon and expanded-graphite exhibit promise to serve as anodes in NIBs because of the cost-effectiveness of carbonaceous materials and suitable charge/discharge plateau. − …”

“…This translates into higher coordination numbers compared to typical carbonate solvents. 19 , 20 Previous studies have shown that glyme-based solvents with sodium salts have two glyme molecules complexing with the cation in the case of diglyme and triglyme systems, and one to two distinct glyme molecules in the solvation shells of tetraglyme systems. 21 The chelating effect is particularly pronounced in longer glymes resulting in increased oxidative stability.…”