DME Solution Research Articles

Liquid-phase synthesis of Li2S and Li3PS4 with lithium-based organic solutions

Sulfide solid electrolytes are widely regarded as one of the most promising technical routes to realize all-solid-state batteries (ASSBs) due to their high ionic conductivity and favorable deformability. However, the relatively high price of the crucial starting material, Li2S, results in high costs of sulfide solid electrolytes, limiting their practical application in ASSBs. To solve this problem, we develop a new synthesis route of Li2S via liquid-phase synthesis method, employing lithium and biphenyl in 1, 2-dimethoxyethane (DME) ether solvent to form a lithium solution as the lithium precursor. Because of the comparatively strong reducibility of the lithium solution, its reaction with sulfur proceeds effectively even at room temperature. This new synthesis route of Li2S starts with cheap precursors of lithium, sulfur, biphenyl and DME solvent, and the only remaining byproduct (DME solution of biphenyl) after the collection of Li2S product can be recycled and reused. Besides, the reaction can proceed effectively at room temperature with mild condition, reducing energy cost to a great extent. The as-synthesized Li2S owns uniform and extremely small particle size, proved to be feasible in synthesizing sulfide solid electrolytes (such as the solid-state synthesis of Li6PS5Cl). Spontaneously, this lithium solution can be directly employed in the synthesis of Li3PS4 solid electrolytes via liquid-phase synthesis method, in which the centrifugation and heat treatment processes of Li2S are not necessary, providing simplified production process. The as-synthesized Li3PS4 exhibits typical Li+ conductivity of 1.85×10−4 S⋅cm−1 at 30 °C.

Kinetics of sulphur dissolution in lithium–sulphur batteries

This study investigates and determines the dissolution kinetics of solid sulphur in DOL:DME solution, a typical electrolyte solution for lithium–sulphur (Li–S) batteries, at four different temperatures, in the range of 17 °C–20 °C. The dissolution kinetics is considered as a function of the solid sulphur-solution interfacial area. The analysis yielded fast dissolution kinetics with a mass transfer coefficient of 2.3 × 10−3 m s−1 at 20 °C but low sulphur solubility of 0.058 S mol lt−1, with the latter being a limiting factor in sulphur dissolution. In later stages, swelling of the solid sulphur region was also observed as a function of time from which the diffusion coefficient of the DOL:DME solution in the solid sulphur was determined. A novel model for the sulphur dissolution and electrolyte impregnation in a Li–S cathode in battery fabrication is presented taking into account the pore size distribution of the cathode host. A computer simulation was carried out and the model and the dissolution parameter values were validated by comparing the predictions with experimental data from in operando microscopy during the dissolution of sulphur and infiltration of the DOL:DME solution in a commercial sulphur-conductive carbon cathode.

Combining experimental and theoretical vibrational spectroscopy to study magnesium aluminum chloride complex electrolytes

Measurements of the Far-IR and Raman spectra of 1:1 MACC-ether electrolytes were carried out. [(μ-Cl)2Mg2]2+ is the major dimer in DME solution and the bands at 250 and 222 cm−1 may be used as markers in the respective IR and Raman spectra. On the other hand, [MgCl]+ stands out in the THF-based electrolyte, where an IR band at 286 cm−1 is here reported for the first time in the literature and may be employed as sensor. The [(μ-Cl)3Mg2]+ dimer, which is usually formed at the 2:1 MACC-THF electrolyte and deemed the electrochemically active species on the electrode, is also identified at the 1:1 ratio. AIMD-simulated IR spectra of the dimer and monomer are in good agreement with the experimental data and were pivotal to characterize the [MgCl(THF)5]+ complex. QC calculations helped assign a few bands in the Raman spectra and Gibbs free energies explained the preferential formation of Mg species in each medium.

Alkyl yttrium complexes of doubly cyclometallated xanthene- and naphthalene-backbone bis(phosphinimine) ligands

The synthesis of a rigid 4,5-bis(triphenylphosphinimino)-2,7-di-tert-butyl-9,9-dimethylxanthene {(Ph3PN)2XT} ligand is outlined, along with a modified synthesis for previously reported 1,8-bis(triphenylphosphinimino)naphthalene {(Ph3PN)2NAP}. Reaction of neutral (Ph3PN)2XT with [Y(CH2SiMe3)3(THF)2] resulted in double cyclometallation, yielding the base-free monoalkyl complex, [({Ph2(C6H4)PN2XT)Y(CH2SiMe3)] (1). Layering a concentrated THF solution of 1 with hexanes at −28 °C afforded THF-coordinated [({Ph2(C6H4)PN}2XT)Y(CH2SiMe3)(THF)]·2THF (1-THF·2THF), with a distorted pentagonal bipyramidal geometry and approximately meridional coordination of the pentadentate {Ph2(C6H4)PN}2XT dianion. Similarly, (Ph3PN)2NAP reacted with [Y(CH2SiMe3)3(THF)2] to afford a THF-coordinated monoalkyl complex, [{(Ph2(C6H4)PN)2NAP}Y(CH2SiMe3)(THF)] (2-THF). Layering a DME solution of 2-THF with hexanes at −28 °C afforded X-ray quality crystals of [[{(Ph2(C6H4)PN)2NAP}Y(CH2SiMe3)(κ2-DME)]·hexane (2-DME·hexane), with a highly distorted pentagonal bipyramidal geometry and a facial coordination mode of the tetradentate {Ph2(C6H4)PN}2NAP dianion.

Schmidt Reaction of Ketones in DME Solution in a Continuous-Flow Microreactor

The Schmidt reaction, the treatment with hydroazoic acid in the presence of a strong acid, converts ketones to amides directly and has been broadly applied in organic synthesis. In this communication, the Schmidt reaction of ketones was carried out in DME solution in a continuous-flow microreactor and gave the amide products. The enclosed small-volume feature of the microreactor made this reaction safe, fast, and cost-effective.

Synthesis, electrochemical behavior and EPR study of organometallic [5]trovacenylthiol (η7-C7H7)V(η5-C5H4SH) and structural characterization of ansa-trithio[3]trovacenophane

Organometallic paramagnetic [5]trovacenylthiol (3) was prepared by acidification of lithium [5]trovacenylthiolate 2, which was synthesized via elemental sulfur oxidative insertion to C–Li bond of [5]trovacenyllithium. [5]Trovacenylthiol (3) was investigated by means of cyclic voltammetry and electron paramagnetic resonance (EPR). However, the reaction of concentrated DME solution of 2 with S2Cl2 unprecedentedly afforded ansa-trithio[3]trovacenophane (6), which was demonstrated by X-ray diffraction analysis. Furthermore, three efficient strategies have been explored to construct S–C, S–Si bond of organometallic alkyl, aryl [5]trovacenyl sulfides (7, 8, 9) and silylthioester (10) in the absence of transition-metal catalyst under mild reaction conditions.

Sterically Encumbered Amidinates and Guanidinates of Calcium and Strontium

AbstractAn attempt to prepare Tmp‐C(NDipp)2Li by treatment of lithium tetramethylpiperidide (Li‐Tmp) with N,N′‐bis(2,6‐diisopropylphenyl)carbodiimide (Dipp‐N=C=N‐Dipp) failed, and ether degradation occurred instead, allowing the isolation of a few crystals of O=CH–CH=C(NH‐Dipp)2 (1) after hydrolytic work‐up. We then investigated calcium and strontium compounds. Metalation of PrisoH [Priso = iPr2N–C(N‐Dipp)2] with [(thf)2Ca{N(SiMe3)2}2] in refluxing hexane for 18 h yielded [{(Me3Si)2N}(thf)Ca(Priso)] (2). At room temperature, very few crystals of [Ca(Priso)2]·hexane (3) precipitated after several months from a saturated hexane solution of 2. KN(SiMe3)2 was added to a THF solution of [(thf)4CaI2] and PrisoH and heated to 60 °C for several hours yielding [(thf)Ca(Priso)(μ‐I)]2 (4). Metalation of PrisoH with [(thf)2Sr{N(SiMe3)2}2] led to formation of [Sr(Priso)2] (5) regardless of the applied stoichiometry. The reaction of N,N′‐bis(2,6‐diisopropylphenyl)benzamidine with KN(SiMe3)2 and [(thf)4CaI2] in THF followed by recrystallization from 1,2‐dimethoxyethane (dme) solution yielded [(dme)Ca{(Dipp‐N)2C–Ph}2] (6). The molecular structures of these compounds are discussed and compared with those of other encumbered complexes of divalent metal ions.

8-Quinolinolate complexes of yttrium and ytterbium: molecular arrangement and fragmentation under laser impact

New 8-quinolinolate (Q) complexes of yttrium (1) and ytterbium (2) were synthesized by the reactions of Cp3Y and Yb[N(SiMe3)2]3 with 3 equiv. of 8-hydroxyquinoline in a DME solution. Single crystal X-ray analysis revealed the trinuclear molecular structure of the compounds Ln3Q9. The LDI-TOFMS investigation displayed that under the laser impact the compounds split off Q(-) anions to give Ln3Q8(+), Ln2Q5(+) and LnQ3(+) moieties. In the negative mode spectra the anions Q(-) and LnQ4(-) were observed. The DFT calculations showed the decreased stability of cationic Ln-quinolinolate as compared with their anionic counterparts. Complex 2 which is used as an emitter in a three-layer OLED displayed a metal-centered emission at 979 nm and an intensity of 50 μW cm(-2) at 15.5 V.

Syntheses and structures of lanthanide borohydrides supported by a bridged bis(amidinate) ligand and their high activity for controlled polymerization of ε-caprolactone, l-lactide and rac-lactide

Metathesis reaction of LLnCl(THF)(2) [L = (Me(3)SiNC(C(6)H(5))N)(2)(CH(2))(3)] with NaBH(4) in a 1 : 1.5 molar ratio in THF (THF = tetrahydrofuran) at 60 °C afforded the monoborohydride LLn(BH(4))(DME) [Ln = Y (1), Nd (2), Sm(3) and Yb(4)] crystallized from DME solution (DME = dimethoxyethane). Crystal structure analyses revealed 1-4 are monomers, in which each metal is ligated by one L ligand, one η(3)-BH(4) group and one DME molecule in a trigonal bipyramid geometry. Complexes 1-4 were found to be very active single-site initiators for the controlled ring opening polymerization of ε-caprolactone (ε-CL) and L-lactide (L-LA) as judged by relatively narrow molecular weight distributions (M(w)/M(n): 1.34-1.50) and experimental values M(n)(exp) were in good agreement with theoretic values M(n)(theo). The highest activity and the best control over the molecular weight for both monomers were found for the system with 2. These monoborohydride complexes can also initiate the ring opening polymerization of rac-LA to gave heterotactically enriched polyLA with Pr (heterotactic enrichment) values in a range of 0.69-0.85 depending on the lanthanide metals and the most effective heterotactic enrichment (Pr) was found for 1 (Pr = 0.85). Moreover, complex 1 initiated the polymerization of rac-LA in a living fashion.

ChemInform Abstract: Reactions of α‐Imino Ketones Derived from Arylglyoxals with (Trifluoromethyl)trimethylsilane; a New Route to β‐Amino‐α‐trifluoromethyl Alcohols.

Abstract The reactions of α-imino ketones, derived from arylglyoxals, with (trifluoromethyl)trimethylsilane (CF 3 SiMe 3 ) in DME solution, in the presence of catalytic amount of CsF, at room temperature, yield O-silylated β-imino alcohols in the chemoselective manner. Subsequent reduction of these products with NaBH 4 in ethanolic solution leads to the corresponding β-(N-alkyl)amino-α-trifluoromethyl alcohols in good to excellent yields. Trifluoromethylation of enantiomerically pure α-imino ketones (with Ar = Ph or p -MeOC 6 H 4 ), bearing as a chiral auxiliary the PhCH(Me) group attached to the nitrogen atom, yields mixtures of diastereomeric products in the ratio of ca. 3:2.

Reactions of α-imino ketones derived from arylglyoxals with (trifluoromethyl)trimethylsilane; a new route to β-amino-α-trifluoromethyl alcohols

The reactions of α-imino ketones, derived from arylglyoxals, with (trifluoromethyl)trimethylsilane (CF 3SiMe 3) in DME solution, in the presence of catalytic amount of CsF, at room temperature, yield O-silylated β-imino alcohols in the chemoselective manner. Subsequent reduction of these products with NaBH 4 in ethanolic solution leads to the corresponding β-(N-alkyl)amino-α-trifluoromethyl alcohols in good to excellent yields. Trifluoromethylation of enantiomerically pure α-imino ketones (with Ar = Ph or p-MeOC 6H 4), bearing as a chiral auxiliary the PhCH(Me) group attached to the nitrogen atom, yields mixtures of diastereomeric products in the ratio of ca. 3:2.

New sandwich complexes of di- and trivalent ytterbium: Reduction of Yb(3+) by a bulky cyclooctatetraenyl dianion

The influence of bulky silyl-substituted cyclooctatetraenyl ligands on the formation and structure of ytterbium sandwich complexes has been investigated. Treatment of anhydrous YbCl 3 with equimolar amounts of [K(DME)] 2(COT TBS) ( 2, COT TBS = [C 8H 6(SiMe 2 t Bu) 2-1,4 ] 2−) and KCp ∗ (Cp ∗ = pentamethylcyclopentadienyl) in DME solution (DME = 1,2-dimethoxyethane) afforded a mixture of neutral Cp ∗Yb(COT TBS) ( 3, purple crystals) and anionic [K(DME) 4][Yb(COT TBS) 2] ( 4, royal blue crystals) which could be separated by selective extraction. In contrast, the closely related reaction of YbCl 3 with equimolar amounts of K 2(DME) 2(COT‴) ( 5, COT‴ = [C 8H 5(SiMe 3) 3-1,3,6] 2−) and KCp ∗ resulted in spontaneous reduction of Yb 3+ to the divalent oxidation state and formation of dark blue-green (DME) 2K(μ-COT‴)YbCp ∗ ( 6) as the sole reaction product. The compounds 3, 4, and 6 were structurally characterized by X-ray diffraction.

Syntheses and crystal structures of lithium derivatives of diphosphanes R 2P–P(SiMe 3)Li · 3L, R = Ph, iPr and iPr 2N, L = THF or DME

The reactions of R 2P–P(SiMe 3) 2 (R = Ph, i Pr and i Pr 2N) with BuLi in THF or DME solution lead to ion-contacted lithium derivatives R 2P–P(SiMe 3)Li · 3THF (R = i Pr, i Pr 2N) with tetrahedrally surrounded Li atoms and to the solvent-separated ionic [Li · 3DME] +[Ph 2P–PSiMe 3] − with an octahedrally surrounded Li atom as confirmed by X-ray crystal structure analysis. The reaction of BuLi with Ph 2P–P(SiMe 3) 2 is accompanied with a significant side-reaction leading to Ph 2P–PPh 2 and to LiP(SiMe 3) 2.

Asymmetric [2,3]‐Rearrangement of Glycine‐Derived Allyl Ammonium Ylids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Asymmetric [2,3]-Rearrangement of Glycine-Derived Allyl Ammonium Ylids

The first examples of highly enantioselective [2,3]-sigmatropic rearrangements of acyclic allylic ammonium ylids are reported. Thus, a range of N-{2'-[(N'-allyl-N',N'-dialkyl)ammonium]}acetyl camphor sultams undergo rearrangement at 0 degrees C in DME solution with high diastereofacial control (up to 99:1 dr) to give allylglycines in generally high yield. The power of the method has been demonstrated in a rapid and efficient synthesis of (R)-allyl glycine.

Radical anion of isolable dialkylsilylene.

By the reduction of an isolable dialkylsilylene, 2,2,5,5-[tetrakis(trimethylsilyl)]-1-silacyclopentane-1,1-diyl (1), with cesium, rubidium, potassium, sodium, and lithium 4,4'-di(tert-butyl)biphenylide in DME at low temperatures, the corresponding silylene radical anion 2 was generated as the first persistent silylene radical anion in solution and characterized by ESR spectroscopy. Radical anion 2 is rather stable at -70 degrees C in DME but decomposes rapidly at room temperature with a half-life time of ca. 20 min. The g-factor and 29Si hyperfine splitting constants (hfs's) of 2 are almost independent of the countercations, indicating that 2 exists as a free ion or a solvent-separated ion pair in a polar DME solution. A very small hfs due to the 29Si nucleus of the divalent silicon (3.0 mT) as well as a very large g-factor (2.0077) indicates that an unpaired electron is accommodated in the vacant 3ppi orbital of silylene 1.

Palladium-catalyzed cross-coupling reactions of arylboronic acids and 2-I- p-carborane

p-Carborane has been arylated on the 2- B-atom in high yields, using the Suzuki–Miyaura reaction. Thus the reaction between 2-I- p-carborane and various arylboronic acids [1-naphthyl-, phenyl-, 4-MeOC 6H 4, 3-CH 3CONHC 6H 4, 4-NCC 6H 4, 3-NO 2C 6H 4], gave the corresponding 2-aryl- p-carboranes in DME solution when reacted in the presence of cesium fluoride and the catalytic Pd 2(dba) 3–dppb system.

(C9H7)YbI(DME)2], the First Indenyl Half-Sandwich Complex of Divalent Ytterbium

The reaction of the naphthalene ytterbium(II) complex (µ-C10H8)[YbI(DME)2]2 (1) with indene proved to be a convenient synthetic route to the novel indenyl half-sandwich ytterbium(II) complex [(C9H7)YbI(DME)2] (2), which is a monomer in the solid state and stable in DME solution, although it rearranges in THF to give the symmetric derivatives [(C9H7)2Yb(THF)2] and [YbI2(THF)2]. The reaction of 2 with equimolar amounts of C5H5Na in DME yields [(C5H5)2Yb(DME)] and [(C9H7)2Yb(DME)].

A Study on the Solvation Phenomena of Some Sodium Salts in 1,2-Dimethoxyethane from Conductance, Viscosity, Ultrasonic Velocity, and FT-Raman Spectral Measurements

Electrical conductances, viscosity, apparent molar adiabatic compressibilities and Fourier transform (FT)-Raman spectra of sodium perchlorate (NaClO4), sodium tetrafluoroborate (NaBF4), and sodium tetraphenylborate (NaBPh4) in 1,2-dimethoxyethane have been reported. All these electrolytes are found to be strongly associated in this solvent medium. Both ion pairs and triple ions are found to be formed though an overwhelming fraction of each of these electrolytes exists as ion pairs. For NaClO4, the solvent-separated ion pairs predominate over the contact species. For NaBF4 and NaBPh4, on the other hand, the contact species are also formed in significant amounts. FT-Raman studies indicate the presence of “spectroscopically free” ClO4-, BF4-, and BPh4- ions in 1,2-dimethoxyethane solution. The ClO4- ion is found to be significantly solvated, whereas BF4- and BPh4- ions are poorly solvated in DME solution.

Synthesis of (phosphine)silver(I) trifluoromethanesulfonate complexes and the molecular structure of di-μ-trifluoromethylsulfonate-(tetrakis-triphenylphosphine)disilver(I)

Reactions of silver trifluoromethanesulfonate (triflate) and equimolar amounts of triphenylphosphine, 1,2-bis(diphenylphosphino)ethane, bis(diphenylphosphino)methane, or 1,1-bis(diphenylphosphino)ethane in either DME or CH2Cl2 solution produced the corresponding 1:1 complexes [(L)Ag(I)(SO3CF3)] (2–5) in >80% yields. A related 2:1 complex [(Ph3P)2Ag(I)(SO3CF3)] (1) was also obtained using 2 equiv. of Ph3Ph. Both 31P NMR variable temperature solution spectra as well as solid state spectra were recorded for the new complexes, and were generally helpful in structural assignments. An X-ray crystallographic study of 1 shows this to be a dimeric complex with bridging triflate ions; the silver atoms having distorted tetrahedral coordination.