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91.
Jolanta Olkowska‐Oetzel Dieter Fenske Petra Scheer Andreas Eichhfer 《无机化学与普通化学杂志》2003,629(3):415-420
Syntheses and Thermal Properties of Cluster Molecules, formed from Groups 11‐13‐16 Elements In the presence of PPh3, CuX (X = Cl, CH3COO) or AgOC(O)C6H5 and GaCl3 react in THF with S(SiMe3)2 or Se(SiMe3)2 to yield [Cu6Ga8Cl4S13(PPh3)6] ( 1 ), [Cu6Ga8Cl4Se13(PPh3)6] ( 2 ), [Ag6Ga8Cl4S13(PPh3)6] ( 4 ) and [Ag6Ga8Cl4Se13(PPh3)6] ( 5 ). The use of PnPr2Ph instead of PPh3 and subsequent layering with n‐hexane leads to the formation of the cluster [Cu6Ga8Cl4Se13(PnPr2Ph)12] ( 3a , 3b ). Reaction of CuCl, GaCl3 and PnPr3 with Se(SiMe3)2 in THF results in the crystallisation of the ionic cluster (HPnPr3)2[Cu2Ga4Cl4Se6(PnPr3)4] ( 6 ). The structures of 1 — 6 were determined by X‐ray single crystal structure analysis. Thermogravimetric measurements of the cluster molecules and powder diffraction patterns of the remaining powders reveal the potential use of them as single source precursor compounds for the synthesis of the related ternary solid state materials. 相似文献
92.
On the Reaction of Germanium with Germanium Tetrachloride and on the Existence of the Oxidechlorides GeOCl2 and GeOCl6 at the Equilibrium The above equilibrium was measured in a Gauge-manometer and the enthalpy of formation and the entropy for GeCl2,g were derived from these results. From total pressure measurements and transport experiments of GeO2 with GeCl4 follows, that the oxidechlorides Ge2OCl6 and GeOCl2 are not present in measurable concentrations, that means the enthalpy of formation of GeOCl2 must be higher than ?327 kJ · mol?1. 相似文献
93.
Carola Griehl Dieter Ströhl Hans Jeschkeit Erich Kleinpeter 《Monatshefte für Chemie / Chemical Monthly》1992,123(6-7):647-654
Summary During the addition of amines to maleylamino acids in general -amino derivatives are formed. In order to change the reactivity within the vinylogous maleyl system we introduced the -benzylester group into the starting compound N-(cis--carboxyacryloyl)-phenylalanine methylester1. The obtained benzylester2 is adding benzylamine in -position yielding N-benzyl--aspartyl(-benzyl)-phenylalanine methylester4. The addition reaction was investigated by1H-NMR-spectroscopy. The structures of the compounds have been confirmed by elemental analysis, IR,1H-NMR and13C-NMR spectroscopy. 相似文献
94.
The laccase catalyzed oxidative dimerization of salicylic esters, a rare example of a laccase-catalyzed carbon-carbon bond formation, was studied. This reaction allows the use of air as stoichiometric oxidant and proceeds in aqueous solution. The preparative scope and the mechanism of the method, which provides a new and convenient access to functionalized biaryls under mild conditions, were investigated. 相似文献
95.
Enantioselective Synthesis of Allyl-, Propargyl-, and 4-En-2-ynyl-amines via 1,2-Addition of Organocerium Reagents to Chiral Aldehyde Imines (E)- and (Z)-Allyl-, propargyl-, and 4-en-2-ynyl-amines 5 and 14 , useful bifunctional building blocks and of pharmaceutical interest, are synthesized in high enantiomeric purity (e.e. ≥ 97%). Key step is the diastereoselective 1,2-addition (d.e. 86 to ≥ 98%) of organocerium reagents to chiral α,β-unsaturated aldehyde imines 3 or 8 to produce adduct amines 4 and 9 (Schemes 1 and 4, resp.). The propargylamine 9 is a substrate for Pd-catalyzed coupling with alkenyl halides to produce the enynylamine 11a and the thienyl-substituted alkynylamine 11b . The chiral auxiliary (S,S)- 2 is removed from 4 and 11 in 3 steps affording the title compounds 5 and 14 . Diastereoisomer enrichment of the hydrochloride of 6 by crystallization is possible. 相似文献
96.
Siebert HC Born K André S Frank M Kaltner H von der Lieth CW Heck AJ Jiménez-Barbero J Kopitz J Gabius HJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,12(2):388-402
The branched pentasaccharide chain of ganglioside GM1 is a prominent cell surface ligand, for example, for cholera toxin or tumor growth-regulatory homodimeric galectins. This activity profile via protein recognition prompted us to examine the binding properties of peptides with this specificity. Our study provides insights into the mechanism of molecular interaction of this thus far unexplored size limit of the protein part. We used three pentadecapeptides in a combined approach of mass spectrometry, NMR spectroscopy and molecular modelling to analyze the ligand binding in solution. Availability of charged and hydrophobic functionalities affected the intramolecular flexibility of the peptides differently. Backfolding led to restrictions in two cases; the flexibility was not reduced significantly by association of the ligand in its energetically privileged conformations. Major contributions to the interaction energy arise from the sialic acid moiety contacting Arg/Lys residues and the N-terminal charge. Considerable involvement of stacking between the monovalent ligand and aromatic rings could not be detected. This carbohydrate binding strategy is similar to how an adenoviral fiber knob targets sialylated glycans. Rational manipulation for an affinity enhancement can now be directed to reduce the flexibility, exploit the potential for stacking and acquire the cross-linking capacity of the natural lectins by peptide attachment to a suitable scaffold. 相似文献
97.
The asymmetric 1,2-addition of trimethylsilyl cyanide to aldehyde SAMP-hydrazones in the presence of titanium tetrachloride and diethylether in dichloromethane at −100°C up to room temperature, removal of the chiral auxiliary and acid hydrolysis affords α-amino acids in high enantiomeric excesses (ee=94-97%). 相似文献
98.
Storsberg J Yao ML Ocal N de Meijere A Adam AE Kaufmann DE 《Chemical communications (Cambridge, England)》2005,(45):5665-5666
The first example of a pi,sigma domino-Heck reaction under concomitant rearrangement of the tetracyclic allylcyclopropane endo,exo-bishomobarrelene (5) is reported; the stereoselective reaction proceeds via an intramolecular insertion of a primarily-formed carbopalladation intermediate into a strained cyclopropane C-C sigma-bond, giving 9. 相似文献
99.
Johanna Sabine Becker Jochen Westheide Anatolij I. Saprykin Horst Holzbrecher Uwe Breuer Hans -Joachim Dietze 《Mikrochimica acta》1997,125(1-4):153-160
For the determination of trace impurities in ceramic components of solid oxide fuel cells (SOFCs), some mass spectrometric methods have been applied such as spark source mass spectrometry (SSMS), laser ionization mass spectrometry (LIMS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and inductively coupled plasma mass spectrometry (ICP-MS). Due to a lack of suitable standard reference materials for quantifying of analytical results on La
x
Sr
y
MnO3 cathode material a matrix-matched synthetic standard-high purity initial compounds doped with trace elements-was prepared in order to determine the relative sensitivity coefficients in SSMS and LA-ICP-MS. Radiofrequency glow discharge mass spectrometry (rf-GDMS) was developed for trace analysis and depth profiling of thick non-conducting layers. Surface analytical techniques, such as secondary ion mass spectrometry (SIMS) and sputtered neutral mass spectrometry (SNMS), were used to determine the element distribution on surfaces (homogeneity) and the surface contaminants of SOFC ceramic layers.Dedicated to Professor Dr. rer. nat. Hubertus Nickel on the occasion of his 65th birthday 相似文献
100.
Synthesis, IR Spectrum, and Crystal Structure of N,N'-Bis(trimethylsilyl)benzamidinium Tetrachloroferrate(III) The title compound [C6H5? C(NHSiMe3)2][FeCl4] is obtained by the reaction of FeCl3 with N,N,N'-tris(trimethylsilyl)benzamidine in the presence of tetrahydrofurane, forming yellow, moisture sensitive crystals. The compound is characterized by its IR spectrum as well as by an X-ray structure determination. Space group P21/n, Z = 8, 5974 independent observed reflexions, R = 0.066. The lattice dimensions are at ?70°C: a = 2110.7, b = 1109.5, c = 2120.4 pm; β = 111.17º. The compound forms ion pairs, in which the H atoms of the amidinium cation are coordinated with one chlorine ligand of the FeCl4? ion in a chelating manner. 相似文献