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The Structure of the Cobalt Oxide/Au Catalyst Interface in Electrochemical Water Splitting
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U. Göbel F. Atamny W. Bensch A. Fester H. Schubert R. Schlögl 《Fresenius' Journal of Analytical Chemistry》1995,353(3-4):320-323
The desorption of copper from copper contaminated Si(100) samples has been investigated by thermal desorption spectroscopy (TDS). The samples have been contaminated with aqueous CuSO4/EDTA solutions. The amount of copper deposited on the Si surface was in the monolayer region as determined by means of ratio-tracer experiments. The copper is adsorbed on the sample surface in two different states, which could be resolved by TDS. By means of STM and XPS measurements it was possible to assign these two desorption peaks to the desorption of copper from carbon deposits, which had already been present before the contamination process, and to the desorption of copper from the bare Si surface. 相似文献
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Fester GW Wagler J Brendler E Böhme U Roewer G Kroke E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(10):3164-3176
H(2)SiCl(2) and substituted pyridines (Rpy) form adducts of the type all-trans-SiH(2*)Cl(2)2 Rpy. Pyridines with substituents in the 4- (CH(3), C(2)H(5), H(2)C=CH, (CH(3))(3)C, (CH(3))(2)N) and 3-positions (Br) give the colourless solids 1 a-f. The reaction with pyrazine results in the first 1:2 adduct (2) of H(2)SiCl(2) with an electron-deficient heteroaromatic compound. Treatment of 1 d and 1 e with CHCl(3) yields the ionic complexes [SiH(2)(Rpy)(4)]Cl(2*)6 CHCl(3) (Rpy=4-methylpyridine (3 d) and 4-ethylpyridine (3 e)). All products are investigated by single-crystal X-ray diffraction and (29)Si CP/MAS NMR spectroscopy. The Si atoms are found to be situated on centres of symmetry (inversion, rotation), and the Si-N distances vary between 193.3 pm for 1 c (4-(dimethylamino)pyridine complex) and 197.3 pm for 2. Interestingly, the pyridine moieties are coplanar and nearly in an eclipsed position with respect to the SiH(2) units, except for the ethyl-substituted derivative 1 e, which shows a more staggered conformation in the solid state. Calculation of the energy profile for the rotation of one pyridine ring indicates two minima that are separated by only 1.2 kJ mol(-1) and a maximum barrier of 12.5 kJ mol(-1). The (29)Si NMR chemical shifts (delta(iso)) range from -145.2 to -152.2 ppm and correlate with the electron density at the Si atoms, in other words with the +I and +M effects of the substituents. Again, compound 1 e is an exception and shows the highest shielding. The bonding situation at the Si atoms and the (29)Si NMR tensor components are analysed by quantum chemical methods at the density functional theory level. The natural bond orbital analysis indicates polar covalent Si-H bonds and very polar Si-Cl bonds, with the highest bond polarisation being observed for the Si-N interaction, which must be considered a donor-acceptor interaction. An analysis of the topological properties of the electron distribution (AIM) suggests a Lewis structure, thereby supporting this bonding situation. 相似文献
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A. Fester und J. Cruellas 《Fresenius' Journal of Analytical Chemistry》1935,100(3-4):123
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Hui‐Jie Cheng Katrin Lippe Edwin Kroke Jörg Wagler Gerrit W. Fester Ya‐Li Li Marcus R. Schwarz Tatyana Saplinova Stefanie Herkenhoff Vladislav Ischenko Jörg Woltersdorf 《应用有机金属化学》2011,25(10):735-747
Polymeric Si/C/O/N xerogels, with the idealized polymer network structure comprising [Si O Si(NCN)3]n moieties, were prepared by reactions of hexachlorodisiloxane (Cl3Si O SiCl3) with bis(trimethylsilyl)carbodiimide (Me3Si NCN SiMe3, BTSC). NMR and FTIR spectra indicate the existence of ‐NCN‐ and Si O Si‐ units in the xerogels and also in the ceramic materials obtained upon pyrolysis. The feasibility of this reaction protocol was confirmed on the molecular level by the deliberate synthesis of the macrocyclic compound [SiPh2 O SiPh2(NCN)]2, the crystal structure and spectroscopic data of which are reported. The influence of pyridine as a catalyst for the cross‐linking reaction was studied. The degree of cross‐linking increased within the polymers with the addition of pyridine. It was shown by the reaction of hexachlorodisiloxane with excess pyridine that the latter appears to activate only one out of the two ‐SiCl3 moieties under formation of hexacoordinated silicon compounds. The crystal structure of Cl3Si O SiCl3(pyridine)2 is presented. Quantum chemical calculations are in support of this adduct being a potential intermediate in the pyridine catalyzed sol–gel process. The ceramic yield after pyrolysis of the Si/C/O/N‐xerogels at 1000 °C, which reaches values up to 50%, was found to depend on the aging protocol (time, temperature), whereas no correlation was found with the amount of pyridine added for xerogel synthesis. The Si/C/N/O‐ceramics obtained after pyrolysis at 1000 °C under NH3 are completely amorphous. Chemically they have to be considered as hybrids between an ideal [SiOSi(NCN)3]n network and glass‐like Si2N2O. The products are mesoporous with closed pores and a broad pore size distribution. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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V. D. Fester M. Froneman T. A. Modro S. M. Vather 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Treatment of dialkyl (or diaryl) phosphites with titanium tetrakis-(diethylamide) at room temperature resulted in a smooth displacement of both ester functions by the diethylamino groups to give bis(diethylamino) phosphorus acid (58–65%). The same results are obtained at ?40° and no evidence of an intermediate product was detected using 1H n.m.r. techniques. Treatment of dimethyl phosphite with titanium tetrakis(n-dibutylamide) resulted in isolation of two products which were identified as bis-(n-dibylamino) phosphorus acid (52%) and methyl-(n-dibutylamino) phosphorus acid (21%). On the other hand, trialkyl (triaryl) phosphates are inert to the titanium reagents. 相似文献
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Analytical and Bioanalytical Chemistry - 相似文献