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1.
139La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C 4H 8O 2) 3/2 [La(ν 3-C 3H 5) 4], [Li(C 4H 8O 2) 2][Cp′ nLa(ν 3-C 3]H 5) 4−n] (Cp′ = Cp(ν 5-C 5H 5); n = 1, 2 and Cp′ = Cp * (ν 5-C 5Me5); N = 1) and Li[R nLa(ν 3-C 3H 4) 4− n] (R = N(SiMe 3) 2; n = 1, 2 and R = CCsIMe 3; n = 4), as well as for neutral compounds for formulae La(ν 3-C 3H 5) 3L n (L = (C 4H 8O 2) 1.5, (HMPT) 2, TMED), Cp′ nLa(ν 3-C 3H 5) 3−n (Cp′= Cp(ν 5-Cp 5H 5), Cp *(ν 5-C 5Me 5); n = 1, 2) and La(ν 3-C 3H 2) 2X(THF) 2 X = Cl, Br, I). Typical ranges of the 139La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum. Zusammenfassung139La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung
]- [La)ν3-C3H5)4, [Li(C4H8)2][Cp′nLa(ν3-C3H5)4−n(Cp′ = Cp(ν5-C5H5); n = 1, 2 und Cp′ = Cp * (ν5-C5Me5); N = 1) und Li[RnLa(ν3-C3H5)4−n (R = B(SiMe3)2; n = 1, 2 und R = CCSiMe3; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν3-C3H5)3Ln (Ln = (C4H8O2)1.5, (HMPT)2, TMED), Cp′n, La(ν3-C3H5)3−n (Cp′ = Cp(ν5-C5H5), Cp * (ν5- Cp5Me5); n = 1, 2) und La(ν3-Cp3H5)2X(THF)2 (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt. 相似文献
2.
Powder X-ray diffraction, 119Sn NMR spectra, and 1H NMR spin–lattice relaxation times, T1, were measured for (CH 3) nNH 4−nSnCl 3 ( n=1–4). From the Rietveld analysis, it is shown that all four compounds crystallize into deformed perovskite-type structures at room temperature. The temperature dependence of 1H T1 was analyzed in terms of the CH 3 reorientation and other motions of the whole cation. Except for the phase transition in CH 3NH 3SnCl 3, which is from monoclinic to rhombohedral at 331 K, 1H T1 was continuously changed at other phase transitions in this compound as well as in the n=2–4 compounds, suggesting that the transitions are not caused by the change of the motional state of the cation but by an instability of the [SnCl 3] nn− perovskite lattice. 相似文献
3.
Reactions of CoX 2·6H 2O (X = Cl −, ClO 4−) with bis(3,5-dimethylpyrazolyl)methane (dmpzm) and formic acid, acetic acid, benzoic acid, salicylic acid, maleic acid, or fumaric acid under the presence of KOH solution produced a new family of Co(II)/dmpzm complexes, [Co(dmpzm) 2L]X· nH 2O (1: L = O 2CH, X = Cl, n = 2; 2: L = OAc, X = Cl, n = 3; 3: L = benzoate, X = ClO 4, n = 1/3; 4: L = salicylate, X = ClO 4, n = 1/3) and [Co 2(dmpzm) 4L](ClO 4) 2· nSolv (5: L = maleate, n = 3, Solv = H 2O; 6: L = fumarate, n = 2, Solv = MeOH). These compounds were structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Compounds 1–4 are mononuclear while 5–6 are binuclear. Each cobalt atom of 1–6 is hexacoordinate, with a distorted octahedral CoN 4O 2 coordination geometry incorporating two N, N′-bidentate dmpzm ligands and one O, O′-bidentate carboxylate ligand. There are rich intra- and intermolecular hydrogen bonds in the crystals of 1–6, thereby forming either 2D hydrogen-bonded networks (1 and 2) or 3D hydrogen-bonded networks (3–6). In addition, the thermal behaviors of 1–6 were also investigated. 相似文献
4.
The syntheses of Bromodisilanes Br nSi 2H 6−n and Iododisilanes I nSi 2H 6−n ( n = 1, 2, 3, 4, 5), starting from caryldisilanes Ar nSi 2H 6−n (Ar = phenyl, -naphthyl, mesityl) are reported. The 29Si-NMR-spectra of all compounds, including 29Si 29Si-coupling constants, have been measured. ZusammenfassungAusgehend von Aryldisilanen ArS2H6−n, (Ar = Phenyl, -Naphthyl, Mesityl) wurden die Bromdisilane BrnSi2H6−n, und Ioddisilane InSi2H6−n, (n = 1, 2, 3, 4, 5) synthetisiert. Die 29Si-NMR-Spektren aller Verbindungen, (eingeschlossen 29Si29Si-Kopplungskonstanten) wurden vermessen. 相似文献
5.
The title cobalt(III) complexes have been investigated by polarized absorption and Raman spectroscopies of the single crystals. The symmetry properties of the d-electron orbitals and of the vibrational modes attributable to the Raman bands of trans(Cl 2)-[CoCl 2(NH 3) n(H 2O) 4−n]Cl complexes ( n = 2, 3, or 4) were examined to elucidated the peculiar observation that ligand substitution causes no splitting of the 15 200-cm −1 absorption band and the 250-cm −1 Raman band. Effects of replacing the NH 3 ligand with H 2O on the electronic structure, atom–atom force constants and vibrational modes of these complex ions are briefly described. 相似文献
6.
Synthesized hydrated lamellar acidic crystalline magadiite (H 2Si 14O 29·2H 2O) nanocompound was used as host for intercalation of polar n-alkylmonoamine molecules of the general formula H 3C(CH 2) nNH 2 ( n = 1–6) in aqueous solution. The original interlayer distance ( d) of 1500 pm, determined by X-ray powder diffraction patterns, increases after intercalation. The values correlated with the number of aliphatic amine carbon ( nc) atoms: d = [(1312 ± 11) + (21 ± 2)] nc. The amount of intercalated amines ( Ns), decreased as nc increased: Ns = [(5.82 ± 0.04) − (0.45 ± 0.01)] nc. The acidic layered nanocompound was calorimetrically titrated with the amines and the thermodynamic data gave exothermic values for all guest molecules, as shown by the correlation: Δ intH = −[(24.45 ± 0.49) − (1.91 ± 0.10)] nc and d = [(1576 ± 16) − (10.8 ± 1.0)]Δ intH. The negative values of the Gibbs energies and the positive entropies also presented the correlations: Δ intG = −[(22.8 ± 0.2) − (0.2 ± 0.1)] nc and Δ intS = [(6 ± 1) + (5 ± 1)] nc, respectively. 相似文献
7.
New efficient routes to the generation of silanones at relatively low temperatures are based on the following reactions: 1. (1) reaction of linear and branched perhydrocarbyldisiloxanes and oligosiloxanes, and of some of their C-functional derivatives, with gallium or indium iodides or bromides; 2. (2) reaction of hydrocarbylchlorosilanes R4−nSiCln (n = 2–4) and SiCl4 with dimethylsulphoxide (with or without Mg or Zn); 3. (3) Autodecomposition of organosilicon compounds containing
and
groups; 4. (4) reaction of R4−nSiCln with metal oxides of high redox potential (with or without the presence of CH3CN).
Insertions of dialkylsilanones into Si---O---Si and Si---O---C linkages as well as into the Si---Cl bond have been studied. 相似文献
8.
Photodecomposition of 10 different molybdenum and tungsten mixed carbonyl complexes, [M(CO) 3(B)(A)]I 2 where B= o-phenanthroline or bipyridyl, A=3-(2-propynyl)thio-4,5-diphenyl-4H-1,2,4-triazole (TRZA) or S-propynyl-2-thio benz-imidazole (BIMDA) and 2(2-propynyl-thio(5-phenyl)-1,3,4-oxadiazole (OXA). M(CO) 3(TRZA)I 2, [M(CO) 2(PPh 3) X(TRZA)I Y]I Z where M=Mo, X, Y and Z=1 and M=W, X and Z=2, Y=0, have been performed at 365 nm in oxygen saturated chloroform at 25 °C. The absorbance spectrum of these complexes have been recorded with the time of irradiation in order to examine the kinetics of photodecay. The apparent rate constant (Kd) for the first-order reaction have been calculated and found to be (3.32–4.79)×10−5 s−1. The primary quantum yields (Φ) has also been calculated and were in the range (8.33–12.1)×10−4. The mechanism of the photodecomposition has been suggested according to the kinetic, and photoproduct analysis data, and is similar to reaction of photo-oxidative degradation of polluted molecules in the water. 相似文献
9.
A calorimetric study was performed for adducts of general formula CdBr 2· nL ( n=1 and 2; L=ethyleneurea (eu) and propyleneurea (pu)). The standard molar reaction enthalpy in condensed phase: CdBr 2(c)+ nL(c)=CdBr 2· nL(c); Δ rHmθ, were obtained by reaction–solution calorimetry, to give the following values for mono- and bis-adducts: −19.54 and −34.59; −7.77 and −19.05 kJ mol −1 for eu and pu adducts, respectively. Decomposition (Δ DHmθ) and lattice (Δ MHmθ) enthalpies, as well as the mean cadmium---oxygen bond dissociation enthalpy, DCd---O, were calculated for all adducts. 相似文献
10.
Structure, electronic state and energy of Si nC − and Si nC −2 ( n=1–7) anions have been investigated using the density functional theory. Structural optimization and frequency analysis are performed at the level B3LYP/6-311G(d). The charged-induced structural changes in these anions have been discussed. The strong C–C bond is also favored over C–Si bonds in the Si nC −m anions in comparison with corresponding neutral cluster. Among different Si nC − and Si nC −2 ( n=1–7) anions, Si 3C −, Si 5C − and Si 2C −2 are most stable. Their stability has a decreasing tendency with the increase in the size of these clusters. 相似文献
11.
Since the discovery of superconductivity in Sr 2CuO 2F 2+δ there has been an increased interest in ternary oxide-fluorides. Sr 2CuO 2F 2+δ is prepared via low temperature ( T = 220 °C) reaction routes. Low temperature fluorination induces an interesting structural rearrangement in the parent compound Sr 2CuO 3, which is a one-dimensional material containing linear chains of vertex sharing CuO 4 squares along the crystallographic b axis. Upon fluorination, one oxide is substituted by two fluorides and Cu 2+ becomes octahedrally coordinated by four oxides and two fluorides. The fluorinated compound Sr 2CuO 2F 2+δ displays the T-type structure (La 2CuO 4). Insertion of excess fluorine, δ, also takes place and this fluorine occupies interstitial sites in the T structure. Although the starting material Ca 2CuO 3 is isostructural to Sr 2CuO 3, Ca 2CuO 2F 2+δ displays the T′ (Nd 2CuO 4) structure due to the smaller radius of Ca 2+ compared to that of Sr 2+. The alkaline-earth palladates with the general formula A2PdO3 (A = Ba, Sr) are isostructural with the A2CuO3(A = Ca, Sr) materials. We prepared the Ba2−xSrxPdO3 (x = 0–2) series and performed low temperature fluorination, which led to the synthesis of the series Ba2−xSrxPdO2F2+δ (0 ≤ x ≤ 1.5). All the compounds in the Ba2−xSrxPdO2F2+δ series show T′ structure (Ca2CuO2F2+δ). Similarities and differences with Sr2CuO2F2+δ and Ca2CuO2F2+δ will be discussed. 相似文献
12.
Nest-shaped cluster [MoOICu 3S 3(2,2′-bipy) 2] (1) was synthesized by the treatment of (NH 4) 2MoS 4, CuI, ( n-Bu) 4NI, and 2,2′-bipyridine (2,2′-bipy) through a solid-state reaction. It crystallizes in monoclinic space group P2 1/ n, a=9.591(2) Å, b=14.820(3) Å, c=17.951(4) Å, β=91.98(2)°, V=2549.9(10) Å 3, and Z=4. The nest-shaped cluster was obtained for the first time with a neutral skeleton containing 2,2′-bipy ligand. The non-linear optical (NLO) property of [MoOICu 3S 3(2,2′-bipy) 2] in DMF solution was measured by using a Z-scan technique with 15 ns and 532 nm laser pulses. The cluster has large third-order NLO absorption and the third-order NLO refraction, its 2 and n2 values were calculated as 6.2×10 −10 and −3.8×10 −17 m 2 W −1 in a 3.7×10 −4 M DMF solution. 相似文献
13.
The epoxidation of cyclopentene with hydrogen peroxide catalyzed by 12-heteropolyacids of molybdenum and tungsten (H 3PMo 12−nW nO 40, n = 1–11), 12-tungstophosphoric acid and 12-molybdophosphoric acid combined with cetylpyridinium bromide as a phase transfer reagent was carried out in acetonitrile. Among 13 heteropolyacids investigated, catalyst of H 3PMo 6W 6O 40 showed the highest activity, giving a conversion of 60% and a selectivity of 95% in the epoxidation of cyclopentene. The fresh catalysts and the catalysts under reaction condition were characterized by UV–vis, FT-IR and 31P NMR spectroscopy, which has revealed that all of the molybdotungstophosphoric acids were degraded in the presence of hydrogen peroxide to form a considerable amount of phosphorus-containing species. The active species resulted from H 3PMo 6W 6O 40 are new kinds of phosphorus-containing species, which is different from {PO 4[WO(O 2) 2] 4} 3−. 相似文献
14.
Halogenated trisilanes X nSi 3H 8−n with X = Cl, Br, I and n = 2–7 as well as the tetrasilanes H 2XSiSiX 2SiX 2SiX 2H have been prepared by dearylation of appropriate aryltrisilanes and aryltetrasilanes (aryl = phenyl, p-tolyl) with either liquid or gaseous hydrogen halides. The compounds have been characterized with elemental analysis as well as 29Si NMR spectroscopy. 相似文献
15.
The new chloro(cyclopentadienyl)silanes Cp′SiH yCl 3−y (Cp′=Me 4EtC 5, y=1: 1; Cp′=Me 4C 5H, y=1: 2; y=0: 3; Cp′=Me 3C 5H 2, y=1: 4 and pentachloro(cyclopentadienyl)disilanes Cp′Si 2Cl 5 (Cp′=Me 5C 5 5, Me 4EtC 5 6, Me 4C 5H 7, Me 3C 5H 2 8, Me 3SiC 5H 4 9) are synthesized in good yields via metathesis reactions. Treatment of 1–9 with LiAlH 4 leads under Cl–H exchange to the hydridosilyl compounds Cp′SiH 3 (Cp′=Me 4EtC 5 10, Me 4C 5H 11, Me 3C 5H 2 12) and to the hydridodisilanyl compounds Cp′Si 2H 5 (Cp′=Me 5C 5 13, Me 4EtC 5 14, Me 4C 5H 15, Me 3C 5H 2 16, Me 3SiC 5H 4 17). Complexes 1–17 are characterized by 1H, 13C, and 29Si-NMR spectroscopy, IR spectroscopy, mass spectrometry and CH-analysis. The structures of 6, 7 and 9 are determined by single-crystal X-ray diffraction analysis. Pyrolysis studies of the cyclopentadienylsilanes 10–12 and disilanes 13–17 show their suitability as precursors in the MOCVD process. 相似文献
16.
When GaAs–Si and GaAs–AlGaAs heterostructures are exposed to γ-quanta, radiation stimulated ordering is observed. However, the gettering efficiency in such systems falls for layer widths more than 1 μm. For this reason we seek effective methods of radiation resistance improvement of materials in which one would expect point radiation defects to be gettered not only at defect boundaries, but also in the active layer volume. S.i.GaAs–s.i.AlxGa1−xAs–nGaAs : Te heterostructures are presented with epitaxial layers (doped with Yb or undoped), obtained by means of LPE (liquid-phase epitaxy). The electron concentration in nGaAs was found to be (1–3)×1018 cm−3 for widths 1–3 μm. The samples were exposed to 60Co γ-quanta with doses of 105–107 rad. Investigations of irradiated samples by means of low-temperature (4.2 K) photoluminescence have shown considerable decrease of exciton halfwidth in the boundary spectra of nGaAs : Te : Yb epitaxial layers in comparison with nGaAs : Te layer spectra. This is caused by background impurity gettering which happens on the s.i.AlxGa1−xAs–nGaAs heteroboundaries as well as in deformed regions in the epitaxial layer volume. Formation of such regions is caused by the difference between the covalent radii of Yb atoms and GaAs lattice atoms. The maximum effect of radiation stimulated gettering of dopants in nGaAs epitaxial layers is observed for Yb concentrations which are equal to 10−4–10−5 atomic fractions in a solution-melt. It is determined that the deformed regions in epitaxial layer volumes and heteroboundaries could be efficient drains for point radiation defects which form under radiation exposure. The investigations carried out showed that the doping of an epitaxial layers by rare-earth impurities provides considerable improvement in forming radiation resistant III–V materials. 相似文献
17.
Dialkyl disulfide-linked naphthoquinone, (NQ-C n-S) 2, and anthraquinone, (AQ-C n-S) 2, derivatives with different spacer alkyl chains (C n: n = 2, 6, 12) were synthesized and these quinone derivatives were self-assembled on a gold electrode. The formation of self-assembled monolayers (SAMs) of these derivatives on a gold electrode was confirmed by infrared reflection-absorption spectroscopy (IR-RAS). Electron transfer between the derivatives and the gold electrode was studied by cyclic voltammetry. On the cyclic voltammogram a reversible redox reaction between quinone (Q) and hydroquinone (QH 2) was clearly observed under an aqueous condition. The formal potentials for NQ and AQ derivatives were −0.48 and −0.58 V, respectively, that did not depend on the spacer length. The oxidation and reduction peak currents were strongly dependent on the spacer alkyl chain length. The redox behavior of quinone derivatives depended on the pH condition of the buffer solution. The pH dependence was in agreement with a theoretical value of E1/2 (mV) = E′ − 59pH for 2H +/2e − process in the pH range 3–11. In the range higher than pH 11, the value was estimated with E1/2 (mV) = E′ − 30pH , which may correspond to H +/2e − process. The tunneling barrier coefficients ( β) for NQ and AQ SAMs were determined to be 0.12 and 0.73 per methylene group (CH 2), respectively. Comparison of the structures and the alkyl chain length of quinones derivatives on these electron transfers on the electrode is made. 相似文献
18.
This short review is concerned with sustainable chemistry and recent research progress in catalysis systems for the use of aqueous hydrogen peroxide or dioxygen. Some achievements in the development of catalysts for epoxidations and for carbon–carbon bond cleavage are presented. Special emphasis is placed on fully inorganic systems, some with the dimeric moiety [M 2O 2(μ-O 2) 2(O 2) 2], (M = V, Mo, W) which have more scope than those containing organic ligands or supports, however robust. Oxoperoxometalate species with or without assembling ligands can be used for homogeneous, two-phase and phase-transfer catalyses and to prepare mesoporous materials (M-MCM-41, M-SBA-15, etc.) and supported catalysts for effective immobilization of activated metal peroxo complexes. Moreover, the decomposition of molybdenum and vanadium oxoperoxo species in water and phosphoric acid leads to an elegant method for preparing H 3+n[PMo 12−nV nO 40]·aq ( n = 2–9) at room temperature, avoiding the tedious synthesis with diethyl ether extraction. Spectrometric, structural and reactivity data on the precursor complexes lead to a more rational approach to catalysis systems and to the discovery of novel classes of precursors and/or catalysts for the selective transfer of oxygen to organic substrates. 相似文献
19.
A dense membrane of La 0.6Sr 0.4Co 0.8Fe 0.2O 3−δ (LSCF) perovskite was prepared by a new chelating agent, ethylene diamine N, N, N′, N′-tetra N-acetyl diamine (EDTNAD). As a potent ligand, EDTNAD provided a facile one-step method to form complexes of the four metal ions, simultaneously. The oxygen permeation flux through the pure perovskite LSCF dense membrane was measured over temperature range of 1073–1223 K, thickness of 0.7–1.0 mm and oxygen partial pressure of 0.1–1.0 bar. Oxidative coupling of methane (OCM) reaction using LSCF disk in the atmospheric membrane reactor and over the temperature range of 1073–1173 K showed a C 2 selectivity of 100% and C 2 yield of 5.01% at 1153 K. Furthermore, OCM reaction data of the membrane reactor were discussed and compared with those of the fixed bed using the same perovskite powder as the catalyst. 相似文献
20.
Lamellar crystalline calcium phenylphosphonate, as anhydrous Ca(HO 3PC 6H 5) 2 and hydrated Ca(HO 3PC 6H 5) 2·2H 2O compounds, were used as hosts for intercalation of polar n-alkylmonoamine molecules of the general formula CH 3(CH 2) nNH 2 ( n=0–4, 7) in water or 1,2-dichloroethane. An increase in the interlayer distance was observed. The exothermic enthalpic values for intercalation increased with the number of carbon atoms and with increasing concentration of the amines. The intercalation followed by a titration procedure in the solid/liquid interface with Ca(HO 3PC 6H 5) 2·2H 2O and Ca(HO 3PC 6H 5) 2 gave the enthalpy/number of carbons correlations: Δ intH=−(1.74±0.43)–(1.30±0.13) nc and Δ intH=−(4.15±0.15)–(1.07±0.03) nc, for water and 1,2-dichloroethane, respectively. A similar correlation Δ intH=−(4.27±0.80)–(1.85±0.21) nc was obtained in water by using the ampoule breaking procedure for Ca(HO 3PC 6H 5) 2·2H 2O. The increase in exothermic enthalpic values with the increase in n-aliphatic carbon atoms is more pronounced for the anhydrous compound and also when using the ampoule breaking procedure. The Gibbs free energies are negative. Positive entropic values favor intercalation in these systems. 相似文献
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