Li-storage and cycling properties of Sn–Sb-mixed oxides, (M1/2Sb1/2Sn)O4, M = In, Fe

The mixed oxide compounds, (M_1/2Sb_1/2Sn)O₄, M = In and Fe are prepared by the high-temperature solid-state reaction, at 800 °C for M = In and at 1,150 °C for M = Fe. High-energy ballmilling is used to reduce the particle size to nm-range. The compounds are characterized by X-ray diffraction, Rietveld refinement, scanning electron microscopy, and Brunauer–Emmett–Teller surface area methods. The Li-storage and cycling properties of the bare and ballmilled compounds are evaluated by galvanostatic cycling at ~0.15 C and in the voltage ranges 0.005–1.0 and 0.005–1.2 V vs. Li up to 50 (or 100) cycles and by cyclic voltammetry (CV) at room temperature. Effect of electrode heat treatment and carbon nanotube (CNT) addition is also studied. Initial reversible capacities in the range 425–550 mAh g^?1 are observed depending on the metal (M) upper cut-off voltage, CNT content and electrode heat treatment. Ballmilled (In_1/2Sb_1/2Sn)O₄ showed a stable capacity of 445 mAh g^-1 up to 30 cycles and 5 % capacity fading after 50 cycles. In all other cases, capacity fading is observed ranging from 9 to 60 %. The CV showed that the main cathodic and anodic peaks occur at 0.15–0.25 V and ~0.5 V vs. Li, respectively, for both M. The reaction mechanism involves alloying–de-alloying reactions of Sn and In with Li₃Sb or Fe acting as conducting matrix, and corroborated by the ex-situ X-ray diffraction data on (In_1/2Sb_1/2Sn)O₄.     

Theoretical studies of the reactions of M+ (M = Ta,W, Re) with CS2

Gas-phase CS₂ activation by M⁺ (M = Ta, W, Re) was studied by the B3LYP density functional method.The geometries for reactants, transition states, and products were completely optimized. CS₂ activation mediated by M⁺ (M = Ta, W, Re) were found to be a spin-forbidden process as a result of the crossing among the multistate energetic profiles. On the basis of the Hammond postulate, this was a typical two-state reactivity reaction. Among the different potential energy surfaces, the crossing points had been explored. The spin–orbit coupling (SOC) was also calculated between the electronic states of different multiplicities at the crossing point to estimate the intersystem crossing probability. For CP1, CP2, and CP4, the computed SOC constants were 80.28, 128.65, and 526.77 cm^?1, which obtained by using one-electron spin–orbit Hamiltonian in Gaussian 09.     

Electronic Structure of TiAl-2M(M=V,Nb,Ta,Cr,Mo,W,Mn) Alloy

1INTRODUCTIONTitaniumaluminidesbasedonY-TiAlarereceivingconsiderableattentionaspo-tentialcandidatesformaterialsinhightemperatureaerospaceapplication.Theirlowdensity,hightemperaturescreepresistance,highoxidationresistanceandstrengthmakesthemexcellentpotentialenginematerials.Howevertheirlowductilityandlowfracturetoughnessatroom'temperaturesaremajorhindrancestotheirpracticaluti-lization.TheTiAlalloymayhaveanelongationabout2%t'},furtherimprovementisnecessarybeforethesematerialscouldbeusedin…     

Solubility of Oxygen in Some 1-1, 2-1, 1-2, and 2-2 Electrolytes as a Function of Concentration at 25°C

The solubility of oxygen has been measured in a number of electrolytes [(LiCl, KCl, RbCl, CsCl, NaF, NaBr, NaI, NaNO₃, KBr, KI, KNO₃, CaCl₂, SrCl₂, BaCl₂, Li₂SO₄, K₂SO₄, Mn(NO₃)₃)] as a function of concentration at 25°C. The solubilities, mol (kg-H₂O)^–1, have been fitted to a function of the molality m (standard deviation < 3mol-kg^–1)

Reaction of 1, 1-Di-p-methoxyphenyl-2, 2-dinitroethylene and 1, 1-Di-O-methoxyphenyl-2, 2-dinitroethylene with 1-Benzyl-1, 4-dihydronicotinamide： Evidence for Concerted Electron-hydrogen Atom Transfer Mechanism

1,1-Di-p-methoxyphenyl-2, 2-dinitroethylene reacts with 1-benzyl-1, 4-dihydronicotinamide (BNAH) in deaerated acetonitrile to give 1,1-di-p-methoxyphenyl-2, 2-dinitroethane,while 1,1-di-O-methoxyphenyl-2, 2-dinitroethylene fails to react with BNAH under the same conditions, which provides evidence for a concerted electron-hydrogen atom transfer mechanism.     

Effect of Solvents on Oxidation of 1, 1′-Bi-2-naphthol

A novel biomimetic catalyst of complex Cu (p-OTs)2/ethanolamine (1 : 1 ) was used to oxidize 1, 1′-bi-2naphthol into xanthene derivatives with a relative high yield in a mixed solvents of dimethyl sulfoxide (DMSO) and CH3OH. The studies on the effect of some solvents on the yield of xanthene derivatives indicates that the yield reduces dramatically with the increase of the content of H2O in the mixed solvents of H2O and DMSO. No product can be obtained when the content of H2O is up to 70%. The cyclic voltammetric study demonstrated that the copper ion in complex Cu(p-OTs)2/ethanolamine(1:1) is reduced via a twostep one-electron reduction process from Cu (Ⅱ) to Cu in the mixture of DMSO and H2O. Water as a poor solvent in respect to the reactants probably hampered the coordination of 1, 1′-bi-2-naphthol to copper/amine complex and led to the insufficient catalytic efficiency of complex Cu(p-OTs),/ethanolamine(1:1).     

Ab initio Study of H2O–HCl (1:1, 1:2, 2:1) Complexes

This paper reports on an ab initio (6-31G**) study of 1:1, 1:2, and 2:1 (H₂O) _n (HCl) _m complexes. Stable configurations of the 1:2 and 2:1 (H₂O) _n (HCl) _m complexes and their geometrical and energy characteristics were determined. The vibrational analysis of the complexes was carried out. The effect of hydrogen bonding due to S₁S₀ and T₀T₁ electronic excitations is considered.     

Synthesis and Crystal Structure of 2-Amino-1, 1-diferrocenylethanol

2-Aminoalcohols are useful intermediates in organic chemistry, for example, they serve for the synthesis of various heterocycles1, chelate complexes2, and for the ring expansion of cycloalkanones3. 2-Aminoalcohols containing ferrocene as bidentate ligand may be converted into multinuclear compounds. Several methods for the preparation of 2-aminoalcohols have been developed including reduction of the trimethylsilyl cyanohydrins4 or β-nitromethyl alcohols5 and treatment of the epoxides with a…     

Photo-induced Coupling Reaction of 1, 1-Diphenyl-2, 2-dicyanoethylene with 10-Methyl-9, 10-dihydroacridine

In a previous communication1, we reported a novel photo-induced coupling of 9-fluorenylidenemalononitrile 1 with the coenzyme NADH model 10-methyl-9, 10-dihydroacridine (AcrH2) to give 9-dicyanomethyl-9-(10-methyl-9-acridinyl)fluorene and proposed a mechanism involving photo-induced electron transfer-proton transfer and radical coupling. This is a scarce mechanism for the reaction of NADH models2, which usually takes place by a formal hydride transfer pathway3. In view of the novelty of t…     

Stereoselective Synthesis of cis-1, 2-cyclopropane Derivatives

IntroductionNumeroussyntheticmethodsofcyclopropanationhavebeenstudied[l1,butmostofthemarenon-stereoselective,oritsproductisthethermodynamicallystableonewithl,2-transconfiguration.Thestereoselectivesynthesesof1,2-cisisomersofcyclopropanederivativesareseldomseeninliterature.Hereinastere-oselectivecycloporpanationviathereactionofarsenicylidewithe1ectrondefi-cientalkenesisreportedinthispaper.ResultsandDiscussionCarbomethoxymethylenetriphenylarl,oritsarsoniumbromideinthepresenceofK,CO,reactswith2…     

The designed synthesis and crystallographic characterization of three novel heterotrimetallic linear complexes of [Et4N][(Ph3P)2{M′S2 MS2Fe}Cl2] (M=Mo,M′=Ag;M=W,M′=Cu,Ag)

The complexes [Et₄N][(Ph₃P)₂{MS₂ MS₂Fe}Cl₂] (M=Mo,M=Ag;M=W,M=Cu, Ag) have been obtained by reaction of [Et₄N]₂[S₂ MS₂FeCl₂] (M=Mo, W) with Cu(PPh₃)₃Cl or Ag(PPh₃)₃NO₃ in MeCN/CH₂Cl₂, respectively. Crystal data for [Et₄N][(PPh₃)₂ {AgS₂MoS₂Fe}Cl₂] (I): triclinic, P (No. 2),Z=2,a=13.41(1)Å,b=15.54(1)Å,c=12.30(1)Å, =105.24(6)°, =94.63(7)°, =101.38(6)°, andV=2399(4)ų. The bond lengths of Mo-Fe bond and the Mo-Ag distance are 2.756(2)Å and 3.033(2)Å, respectively. Crystal data for [Et₄N][(PPh₃)₂ {AgS₂WS₂Fe}Cl₂] (II): triclinic, P (No. 2),Z=2,a=13.457(5))Å,b=15.601(6)Å,c=12.338(4)Å, =105.20(3)°, =94.61(4)°, =101.43(4)°, andV=2426(2)ų. The bond length of W-Fe bond and the W-Ag distance are 2.786(2)Å and 3.076(1)Å, respectively. Crystal data for [Et₄N][(PPh₃)₂ {CuS₂WS₂Fe}Cl₂] (III): triclinic, P (No. 2),Z=2,a=13.498(5)Å,b=15.372(4)Å,c=12.340(4)Å, =105.54(2)°, =93.32(3)°, =101.40(3)°, andV=2401(1)ų. The bond lengths of W-Fe bond and the W-Cu bond are 2.800(1)Å and 2.851(1)Å, respectively.     

Grignard Addition to Quinoxalinium Salt： Synthesis of 1, 2-Dihydroquinoxaline and 1, 2, 3, 4-Tetrahydroquinoxaline Derivatives

Nucleophilic addition of organometallics to imines or iminium ion has received greatattention in recent years, especially in the field of asymmetric synthesis1. Addition ofthe nucleophilic reagents to quinoxalines was proved to be a useful method for thes…     

Co-cation Conduction in Solid Solutions (K1 – xRbx)4P2O7–M2P2O7(M = Ca,Sr, Cd,Ba): Dependence on the Nature and Concentration of Cations M2+

Solid solutions of the structure -K₄P₂O₇, which have the composition (K_{1 – x} Rb _x )_3.8M_0.1P₂O₇(M = Ca, Sr, Cd, Ba) and (K_{1 – x} Rb _x )_{4 – 2y} Ca _y P₂O₇(y= 0.025–0.20), are synthesized. The solutions' electroconductivity is studied in the temperature range 400–600°C. The concentration dependences of the conductivity and the activation energy for conduction have extremums at x 0.6, which points to the polyalkaline effect. The effect increases with decreasing radius of cation M²⁺and with increasing concentration of calcium cations, which is explained by an increased energy nonequivalence of positions in the cation sublattice accessible to alkali ions.     

Mechanochemical synthesis,structure, and properties of solid solutions of alkaline earth metal fluorides: Ma1−xMbxF2 (M: Ca,Sr, Ba)

The capability of mechanochemical synthesis for the formation of solid solutions of alkaline earth metal fluorides M^a_1−xM^b_xF₂ (M: Ca, Sr, Ba) was tested by fluorination of metal acetates and metal hydroxides with ammonium fluoride directly at milling. Evidence was found for a mutual substitution of cations on their lattice positions in Ca_1−xSr_xF₂ and Ba_1−xSr_xF₂ samples. For the Ba/Ca-system this synthesis route is only partially successful. X-ray diffraction and ¹⁹F MAS NMR spectroscopy were used to characterize all samples concerning their crystal structure and local fluorine coordination. Calculations of ¹⁹F chemical shifts with the superposition model along with probability calculations for the intensity of the individual ¹⁹F lines, performed in dependence on the molar composition of the samples, perfectly agree with the experimental findings. The fluoride ion conductivity of as-prepared samples, determined by temperature dependent DC conductivity measurements, is significantly higher than those of crystalline binary fluorides. Moreover, a higher F⁻ ion conductivity is observed for samples with higher mixing grade in the Ca/Sr-and the Ba/Sr-systems.     

Electroconductivity of Solid Solutions Cs3–2x M x PO4 (M = Ba, Sr, Ca, Mg)

Solid solutions Cs_{3 – 2x} M _x PO₄ (M = Ba, Sr, Ca, Mg) are synthesized and their thermal behavior and electroconductivity are examined. Adding elements of Subgroup IIA of the periodic table into cesium orthophosphate shifts the phase transition, which occurs in pure Cs₃PO₄ at 450–620°, towards lower temperatures and raises the cesium cation conductivity at low temperatures. The electroconductivity of a high-temperature modification of Cs₃PO₄ is weakly dependent on the presence and concentration of such additives, which points to structural disordering of the cesium sublattice.     

Pulse radiolysis study of energy transfer processes in Xe–M mixtures (M=CH2F2,CHF3,CHF2Cl,CHFCl2 and CF3Cl)

The time-resolved spectroscopy measurements were used to study the kinetics of energy transfer process in the pulse radiolysis of xenon- fluoro- and chlorofluoromethanes mixtures. The main channel, at xenon pressure above 40 Torr, seems to be of third order, while at lower xenon pressures the second order process was the main one.     

Synthesis and Crystal Structure of 2-Amino-I, 1-diferrocenylethanol

2-Amino-l,l-diferrocenylethanol 2 was prepared by reduction of trimethylsilylcyanohydrin ether of diferrocenyl ketone. The crystal structure of 2 was further defined by X-raydiffraction.