Cesium Derivatives Research Articles

Ternary cesium(rubidium) tungstates: production and impedance spectroscopy

The work is aimed at the directed synthesis of new phases of tungstates containing mono-, tri-, and tetravalent metals, as well as the determination of their crystallographic, thermal, and electrophysical properties. The study used the method of solid-phase synthesis to obtain tungstate phases with composition MRA0.5(WO4)3 (M – singly, R – triply-, and A – tetra-charged elements) within the temperature range of 400–750 °С. Their crystallographic and thermal characteristics were determined. The synthesized ternary tungstates crystallizing in a hexagonal system were studied using differential scanning calorimetry. The technique revealed an increase in the melting temperatures of compounds with increasing ionic radius of the trivalent cation in the series CsRTi0.5(WO4)3 (R = Al, Cr, Ga, Fe, In). The same correlation is observed when switching from rubidium to cesium derivatives. The thermal stability of ternary titanium and hafnium tungstates was compared. The melting temperatures of RbRTi0.5(WO4)3 are about 20 °С higher than those of their hafnium counterparts. The dielectric characteristics of CsRTi0.5(WO4)3 (R = Fe, Cr) belonging to the ternary tungstate family were analyzed via impedance spectroscopy. The temperature and frequency dependences of the conductivity of ternary tungstates at different frequencies (1 Hz – 1 mHz), measured in heating and cooling modes, are characterized by a slight temperature hysteresis, reaching 10-2–10-3 S/cm in the high-temperature region at activation energy values of 0.4–0.5 eV. The impedance frequency spectra measured within the range of 1 Hz – 1 mHz at different temperatures confirm the ion-conducting properties of the sample, which allows the obtained phases to be considered promising solid electrolytes.

Chiral N-tert-Butylsulfinyl Imines: New Discoveries.

In this account the reactions of chiral N-tert-butylsulfinyl imines with organometallic reagents such as organoalkaline (lithium, sodium, potassium and cesium derivatives), organomagnesium, organozinc, organoboron, organoaluminium, organoindium and organosilicon compounds is comprehensively described. The reactivity in all cases is derived to synthetic applications in order to prepare interesting organic nitrogenated molecules, especially in the field of alkaloid compounds.

Synthesis and characterization of silver and cesium derivatives of Na8[GaSiO4]6(OH)2 sodalite

Gallosilicate hydroxy sodalite, Na8[GaSiO4]6(OH)2 was synthesized at low temperature by hydrothermal method (373 K) and further the sodium ions were partially exchanged with silver and cesium. The obtained products were characterized by IR spectroscopy, X-ray powder diffraction, MAS NMR, TGA and SEM. Parent hydroxy sodalite and its silver and cesium derivatives show cubic symmetry with a space group \(P\bar 4\) 3n. The crystal structures were refined by Rietveld method. The unit cell parameter, a = 8.8527 A for parent hydroxy sodalite, 8.8342 A for the silver derivative and 8.9367 A for cesium one. The 29Si MAS NMR of parent hydroxy sodalite confirms the alternating Ga and Si ordering in sodalite framework, while 23Na MAS NMR shows the effect of cation substitution. The SEM pictures are very regular and show sharp growth for parent sodalite, while the crystal morphology remains nearly same for the silver and cesium derivatives.

Acidic characterization and activity of (NH4)xCs2.5−xH0.5PW12O40 catalysts in the esterification reaction of oleic acid with ethanol

Ammonium and cesium derivatives from H3PW12O40 (H3PW), namely (NH4)xCs2.5−xH0.5PW12O40 (x=0.5, 1, 1.5, 2), were synthesized and structurally characterized by FT-Raman spectroscopy, and their thermal stability was evaluated by FTIR and TGA/DTA. The acidity was characterized by the adsorption/desorption of gaseous pyridine, by FTIR and TGA/DTA as well as by the reaction of oleic acid and ethanol. The stability of the mixed salts regarding the Keggin structure was much higher than the parent acid, with the onset decomposition around 520°C. Nonetheless, calcination up to 300°C is recommended for the integrity of the mixed salt. The FTIR of adsorbed pyridine displayed only Brønsted acidic sites, which was confirmed by TGA measurements of the formation of Py–H+⋯Py adducts. The best esterification result was for (NH4)2Cs0.5H0.5PW12O40 with TOF=1.314molEOmol−1protons−1 with a 1:6 (oleic acid:ethanol) molar ratio, at 80°C and 10wt% catalyst in relation to the acid.

Isomorphism in Alkali Metal Uranophosphates APUO6 · nH2O

A possibility for the isomorphous substitution of sodium, potassium, and rubidium ions for hydroxonium ion in uranophosphoric acid HPUO6 · 4H2O was found, and characteristics of the process were estimated. These solid solutions can be described by the regular model. The lithium and cesium derivatives do not form solid solutions with the hydroxonium derivatives.

Photoinduced ferrimagnetic systems in Prussian blue analogues C(I)xCo4[Fe(CN)6]y (C(I) = alkali cation). 3. Control of the photo- and thermally induced electron transfer by the [Fe(CN)6] vacancies in cesium derivatives.

We synthesized a series of CoFe Prussian blue analogues along which we tuned the amount of cesium cations inserted in the tetrahedral sites of the structure. Structure and electronic structure have been investigated, combining XANES, infrared spectroscopy, powder X-ray diffraction experiments, and magnetization measurements. The change of the magnetization induced by light along the series shows that the efficiency of the photoinduced magnetization, evidenced a few years ago in similar compounds by Hashimoto et al. (Sato, O.; Iyoda, T.; Fujishima, A.; Hashimoto, K. Science 1996, 272, 704-705; Sato, O.; Einaga, Y.; Iyoda, T.; Fujishima, A.; Hashimoto, K. J. Electrochem. Soc. 1997, 144, L11-L13; Sato, O.; Einaga, Y.; Iyoda, T.; Fujishima, A.; Hashimoto, K. J. Phys. Chem. B 1997, 101, 3903-3905; Einaga, Y.; Ohkoshi, S.-I.; Sato, O.; Fujishima, A.; Hashimoto, K. Chem. Lett. 1998, 585-586; and Sato, O.; Einaga, Y.; Fujishima, A.; Hashimoto, K. Inorg. Chem. 1999, 38, 4405-4412), depends on a compromise between the number of excitable diamagnetic pairs and the amount of [Fe(CN)6] vacancies giving the network flexibility. Besides the efficiency of the photoinduced process, the amount of [Fe(CN)6] vacancies also controls a thermally induced electron transfer.

Structural Diversity in Molecular Structures of MP(H)R Species (M = K, Rb, Cs)

The molecular structures of the potassium, rubidium, and cesium derivatives of two different primary phosphanes, namely 2,4,6-tri-t-butylphenylphosphane and 2,6-dimesityl-phenyl-phosphane, are discussed.

Molecular Structures of the Heavier Alkali Metal Salts of Supermesitylphosphane: A Systematic Investigation.

The molecular structures of the rubidium and cesium derivatives of supermesitylphosphane [i.e., (2,4,6-(t)Bu(3)C(6)H(2))PH(2) = (t)Bu(3)MesPH(2)] as well as several base adducts of these are reported. Sodium hydride, potassium hydride, rubidium metal, and cesium metal react with (t)Bu(3)MesPH(2) in tetrahydrofuran solution at room temperature to produce MPRH salts 1-4 [M = Na (1), K (2), Rb (3), Cs (4); R = (t)Bu(3)Mes] in good yields. X-ray-quality crystals of 2 and 3 were obtained by slow evaporation of solutions of the corresponding MP(H)(t)Bu(3)Mes species dissolved in toluene/thf. Complex 4 was crystallized from hot toluene. On the other hand, slow evaporation of a toluene/tetrahydrofuran solution of CsP(H)(t)Bu(3)Mes (4) produces crystals of the composition {[CsP(H)(t)Bu(3)Mes](2)(&mgr;-THF)(0.9).toluene}(x)() (5). Crystallization of 4 in the presence of pyridine yields crystals of {[CsP(H)(t)Bu(3)Mes](2)(&mgr;-pyridine)}(x)() (6). Also, crystallization of complexes 3 and 4 from toluene/N-methylimidazole (N-MeIm) gives the isomorphous complexes {[RbP(H)(t)Bu(3)Mes](2)(&mgr;-N-MeIm)}(x)() (7) and {[CsP(H)(t)Bu(3)Mes](2)(&mgr;-N-MeIm)}(x)() (8), respectively. However, crystallization of 4 from toluene in the presence of bidentate or polydentate bases such as dimethoxyethane or pentamethyldiethylenetriamine does not result in incorporation of these bases into the lattice. Instead, the toluene solvate {[CsP(H)(t)Bu(3)Mes](2)(eta(3)-toluene)(0.5)}(x)() (9) is obtained. On the other hand, crystallization of 4 from toluene/ethylenediamine gives the base adduct {[CsP(H)(t)Bu(3)Mes](2)(&mgr;-ethylenediamine)}(x)() (10). Complex 3 crystallizes in the triclinic space group P&onemacr;. Crystal data for 3 at 218 K: a = 6.71320(10) Å, b = 10.5022(2) Å, c = 14.9733(3) Å, alpha = 91.3524(13) degrees, beta = 102.5584(13) degrees, gamma = 107.7966(14) degrees; Z = 1; R(1) = 6.55%. Complex 4 crystallizes in the triclinic space group P&onemacr;. Crystal data for 4 at 223 K: a = 7.0730(14) Å; b = 10.395(2) Å; c = 14.933(2) Å; alpha = 81.97(1) degrees; beta = 76.35(2) degrees; gamma = 71.824(14) degrees; Z = 1; R(1) = 4.56%. Complex 5 crystallizes in the monoclinic space group P2(1)/c. Crystal data for 5 at 243 K: a = 15.039(2) Å; b = 16.152(3) Å; c = 20.967(5) Å; beta = 91.53(2) degrees; Z = 4; R(1) = 4.83%. Complex 6 crystallizes in the orthorhombic space group Pbcn. Crystal data for 6 at 298 K: a = 14.686(2) Å; b = 21.295(5) Å; c = 28.767(5) Å; Z = 8; R(1) = 5.61%. Complex 7 crystallizes in the orthorhombic space group Pbcn. Crystal data for 7 at 218 K: a = 14.5533(2) Å; b = 21.4258(5) Å; c = 28.5990(5) Å; Z = 8; R(1) = 4.61%. Complex 8 crystallizes in the orthorhombic space group Pbcn. Crystal data for 8 at 219 K: a = 14.6162(2) Å; b = 21.3992(3) Å; c = 28.7037(2) Å; Z = 8; R(1) = 3.57%. Complex 9 crystallizes in the triclinic space group P&onemacr;. Crystal data for 9 at 293 K: a = 11.147(4) Å; b = 14.615(4) Å; c = 14.806(5) Å; alpha = 70.57(3) degrees; beta = 71.85(3) degrees; gamma = 72.93(2) degrees; Z = 2; R(1) = 5.13%. Complex 10 crystallizes in the triclinic space group P&onemacr;. Crystal data for 10 at 173 K: a = 10.5690(4) Å; b = 15.0376(5) Å; c = 15.3643(5) Å; alpha = 111.8630(10) degrees; beta = 100.4120(10) degrees; gamma = 97.4820(2) degrees; Z = 2; R(1) = 4.87%. A common feature of the molecular structures of complexes 2-10 is an infinitely extended polymeric ladder framework in the solid state. Both solution and solid-state NMR data are presented.

Tris(trimethylsilyl)silanides of the Heavier Alkali Metals—A Structural Study

AbstractTransmetalation reactions between bis(hypersilyl)zinc Zn[Si(SiMe3)3]2 and alkali metals have already been established as a facile route to powders of the solvent‐free potassium, rubidium, and cesium derivatives of tris(trimethylsilyl)‐silane (hypersilane, (Me3Si)3SiH).[1,2] By the use of boiling n‐heptane as the solvent, the hitherto unknown NaSi(SiMe3)3 (1) along with the previously synthesized KSi(SiMe3)3 (2) have now been obtained as colorless crystalline materials. Information from NMR and Raman spectra in conjunction with the acute Si‐Si‐Si angles found in their molecular structures indicate mainly ionic bonding. This was verified by population analyses of suitable model systems. Both hypersilanides[2] consist of cyclic dimers [MSi(SiMe3)3]2 (1a, M = Na; 2a, M = K) with almost planar M2Si2 rings (Na‐Si = 299 pm (av); K‐Si = 339 pm (av)), which are linked up into coordination polymers. In a similar manner to the related rubidium and cesium derivatives, a pentane suspension of the potassium compound afforded a yellow solution on addition of benzene, from which the crystalline, bright yellow tris(benzene) solvate 2·(benzene)3 (2b) was isolated. Complex 2b consists of monomers containing short K‐Si bonds (332–334 pm) and three η6‐bonded benzene molecules. No solvate of 1 was obtained under these conditions. However, on crystallization from pure benzene, crystals of (1)2·benzene (1b) were isolated (Na‐Si = 302 pm (av)). Benzene was found to be intercalated between rods of coordination polymers of (1)2. In addition, the influence of π or s̀ donors on the molecular and crystal structures of hypersilylrubidium (3) and cesium (4) was investigated. The structures of the tetrahydrofuran solvate (4)2·THF (4c), the biphenylene/pentane complex (4)2·biphen·(pentane)0.5 (4b) along with the known toluene solvates (3)27dot;toluene (3a) and (4)2·(toluene)3 (4a)[1a] are compared. Finally, an example is presented of how the alkali metal hypersilanides could be utilized in preparing extremely bulky stannanide anions.

Determination of the low temperature 2D and 3D structures of the second stage cesium graphitide

Abstract The structure of stage-2 cesium derivatives CsC 24 was investigated using X-ray diffraction. The 2D and 3D arrangements of the cesium atoms in pure CsC 24 were deduced from Laue diffractograms and rotating crystal patterns. Below 165 K, the 2D structure is formed mainly of a 2.54 × 2.54 R 14.5 ° incommensurate structure with 2 × 2 R 0 ° commensurate domains. At 140 K, while the cesium incommensurate layers get 3D stacked, the 2 × 2 R 0 ° commensurate layers are randomly distributed in the structure. The incommensurate cesium layers are arranged in a 2D modulated stacking, but at lower temperatures this structure is partially replaced by a rhombohedral stacking in which the cesium atoms are modulated along the c -axis owing to the dominating influence of graphitic host. In slightly oxidized compounds, the presence of impurities induces the formation of additional 2.23 × 2.23 R 25.5 ° incommensurate domains which are separated from the structures already observed in pure compounds. These stage-2 domains of composition CsC 20 are characterized by a large interlayer distance. We suggest that oxygen suboxide impurities at the edge of the domains are at the origin of this particular dense structure.

The Liquid/Solid Alkylation of Alkali Metal Pyrazolates

AbstractThe reactions of the lithium, sodium, potassium and cesium derivatives of 3‐methyl‐5‐carbomethoxy‐pyrazole, of 3‐methyl‐5‐ethyl‐pyrazole and of 3‐methyl‐5‐methoxy‐methylene‐pyrazole with methyl iodide, allyl bromide and benzyl chloride were investigated in 1,2‐dimethoxy‐ethane solution and at a liquid/solid interface (suspension of the pyrazole in a 1:1 mixture of n‐hexane and n‐heptane). Comparison of the ratios of the two nitrogen alkylated products formed from the reaction in solution and at the liquid/solid interface, suggests that the latter ratio is determined by the size of the alkali metal cation and by the presence of a coordination centre placed non‐symmetrically with respect to the mirror plane passing through the nitrogen‐nitrogen bond. It is suggested that a “cation in the way” effect is responsible for the liquid/solid‐interface alkylation results.