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301.
L. P. Hart C. R. Cornthwaite H. Hebberling E. Roßmann F. J. Peters A. W. Pamfilow J. N. Rossljakowa und N. W. Smirnow 《Fresenius' Journal of Analytical Chemistry》1938,115(7-8):280-281
Ohne Zusammenfassung 相似文献
302.
P. A. Mc Donald E. M. Campbell A. Snarski I. J. Starik A. S. Smagina J. A. Bottema R. D. Evans A. Piccard L. Meylan A. B. Werigo G. Herzog H. Fränz C. Weiß L. D. Roberts W. Kosmath O. Gerke G. Aliverti G. Rosa O. Erbacher K. Philipp Marthe Leblanc R. Großmann und P. L. Bobin 《Fresenius' Journal of Analytical Chemistry》1938,114(1-2):38-43
Ohne Zusammenfassung 相似文献
303.
Gisbert Großmann Gisela Ohms Kerstin Krüger Konstantin Karaghiosoff Klaus Eckstein Josef Hahn Andreas Hopp Olga L. Malkina Peter Hrobarik 《无机化学与普通化学杂志》2001,627(6):1269-1278
Diselenadiphosphetane Diselenides and Triselenadiphospholane Diselenides – Synthesis and Characterization by 31P and 77Se Solid‐State NMR Spectroscopy 1,3‐Diselena‐2,4‐diphosphetane‐2,4‐diselenides (RPSe2)2 with R = Me, Et, t‐Bu, Ph, 4‐Me2NC6H4, 4‐MeOC6H4 have been synthesized by different methods. The insoluble compounds were investigated by 31P and 77Se solid‐state NMR and the purity of the compounds has been checked by their CP MAS sideband NMR spectra. The structure of the investigated compounds has been confirmed by the isotropic and anisotropic values of the chemical shifts and the 1JP–Se coupling constants. In addition, two new 1,2,4‐triselena‐3,5‐diphospholane‐3,5‐diselenides, (RPSe2)2Se (R = Me, Et), formed under similar synthesis conditions, were investigated. Their structure was derived from the 77Se satellites of 31P solution spectra and from solid‐state spectra. For (t‐BuPSe2)2 the experimentally obtained principal values of phosphorus and selenium shielding tensors are compared with values from IGLO calculations (HF und SOS DFPT). The calculated orientations of the principal axes are discussed. 相似文献
304.
Xinzhe Shi Sihan Li Melanie Reiß Anke Spannenberg Thorsten Holtrichter-Rßmann Fabian Reiß Torsten Beweries 《Chemical science》2021,12(48):16074
The structure, bonding, and reactivity of small, highly unsaturated ring systems is of fundamental interest for inorganic and organic chemistry. Four-membered metallacyclobuta-2,3-dienes, also referred to as metallacycloallenes, are among the most exotic examples for ring systems as these represent organometallic analogs of 1,2-cyclobutadiene, the smallest cyclic allene. Herein, the synthesis of the first examples of 1-zirconacyclobuta-2,3-dienes of the type [Cp′2Zr(Me3SiC3SiMe3)] (Cp′2 = rac-(ebthi), (ebthi = 1,2-ethylene-1,1′-bis(η5-tetrahydroindenyl)) (2a); rac-Me2Si(thi)2, thi = (η5-tetrahydroindenyl), (2b)) is presented. Both complexes undergo selective thermal C–H activation at the 7-position of the ansa-cyclopentadienyl ligand to produce a new type of “tucked-in” zirconocene system, 3a and 3b, that possesses a η3-propargyl/allenyl ligand. Both types of complexes react with carbonyl compounds, producing enynes in the case of 2a and 2b, as well as η1-allenyl complexes for 3a and 3b. Computational analysis of the structure and bonding of 2a and 3a reveals significant differences to a previously described related Ti complex. All complexes were fully characterised, including X-ray crystallography and experimental results were supported by DFT analysis.A detailed study of structure, bonding and reactivity of new 1-zirconacyclobuta-2,3-dienes is presented in comparison to a lighter Ti analog. We found a unique C–H activation at the widely used rac-(ebthi) ligand for that only occurs for Zr. 相似文献
305.
Gerhard Maier Jrg Haußmann Marcus Dietlmeier Susanta Banerjee 《Macromolecular Symposia》1999,142(1):85-99
Several series of poly(arylene ether)s with trifluoromethyl substituents were prepared and characterized. These materials are potential candidates for the use as low dielectric constant insulators (intermetal dielectrics, IMD, and interlayer dielectrics, ILD) on microchips. Thermal stability up to 450 °C and a dielectric constant below 3 preferably below 2.5) is required for this application. The thermal stability of the poly(arylene ether)s was increased from 320°C to more than 500 °C by optimization of the structure of the repeating unit. The dielectric constant of one of the most promising structures was determined to be 2.8. In addition, plasma polymerized thin films from hexafluorobenzene, tetrafluorobenzene, perfluorotoluene and perfluorodecaline were prepared and characterized with respect to solubility, dielectric constant, adhesion, and thermal stability. 相似文献
306.
The intermetallic compounds CaCuGe, CaAuIn, and CaAuSn can be prepared from the elements in sealed tantalum tubes or in glassy carbon crucibles in a high-frequency furnace. Their crystal structures were determined from single crystal X-ray data. The three compounds crystallize with the same subcell structure (KHg2), however, they form three clearly perceptible superstructures with different unit cells, but all in space groups Pnma: a = 2124.9(6) pm, b = 436.0(2) pm, c = 749.4(5) pm, Z = 12, wR2 = 0.0789, 1303 F2 values, 56 variables for CaCuGe (own structure type), a = 738.2(1) pm, b = 459.4(1) pm, c = 839.4(2) pm, Z = 4, wR2 = 0.0651, 656 F2 values, 20 variables for CaAuIn (TiNiSi type), a = 3690.3(3) pm, b = 470.5(1) pm, c = 813.6(2) pm, Z = 20, wR2 = 0.1294, 1730 F2 values, 92 variables for CaAuSn (new structure type). The three structures may be considered as superstructures of the KHg2 type with an ordered arrangement of the transition metal and germanium (indium, tin) atoms on the mercury position. Each calcium atom in the structures of CaCuGe, CaAuIn, and CaAuSn has an distinctly ordered near-neighbor environment of six transition metal (T) and six p element (X) atoms in the form of two counter-tilted T3X3 hexagons. All known superstructures of the KHg2 type are described in terms of a group-subgroup scheme. 相似文献
307.
Monocrystalline semiconductor wafers made of silicon represent the base material for microelectronic devices. The transfer of the precursor material quartz into a 300 mm wafer deposited with an epitaxial layer requires a multitude of process steps, part of which are determined by chemical reactions. This article has introduced into the manufacturing of semiconductor silicon and the processes etching, polishing, cleaning and epitaxy. This technology branch, though, is distinguished by extreme requirements regarding surface perfection and cleanliness, which may be expressed in atomic layers (surface roughness of the wafers) and ppt (contamination of chemicals) 相似文献
308.
309.
R. Preußmann 《Nachrichten aus der Chemie》1979,27(10):653-653
310.
H. Fischer R. Svagera H. Ebel M. F. Ebel B. Schoßmann 《Fresenius' Journal of Analytical Chemistry》1995,353(3-4):473-477
A method of nondestructive depth profiling in near surface regions of solids is described. Models have been discussed from which algorithms for evaluation of measured data are obtained. The algorithms, based on standard profiles with free parameters, have been adjusted to the data resulting from angle resolved XPS (ARXPS) by means of least squares fits. Depth profile analyses and segregation studies were performed on Pt–Ni and Fe–S specimens. 相似文献