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61.
The ternary phases existing on the quasi binary section CoSi/FeSi and CoSi2/β‐FeSi2 have been investigated by solid state reactions and chemical transport. The solid solution serie CoxFe1‐xSi can be described as a regular solution. The transport behaviour calculated is in good agreement with the experiments. The phases have been characterized by X‐ray powder diffraction, EDX and ICP‐OES. The temperature dependence of the resistivity has been measured from 20 K up to room temperature on single crystals. 相似文献
62.
Cyclic Silicic Acid Derivatives By reaction of SiCl4 with oxygen at elevated temperatures a number of chlorsiloxanes consisting of more or less fused rings can be prepared of which those components of low molecular weight can be separated by combining distillation and crystallization. Methyl and ethyl esters of silicic acids are obtained by reaction with methyl or ethyl nitrite, resp. The compounds are characterized by silicon n.m.r. and mass spectroscopy. 相似文献
63.
Kinetic investigations of thermo-controlled two-step reactions between an uretdione cross-linker and OH-groups are undertaken. Non-isothermal DSC measurements are chosen for the determination of the kinetic parameters (E, A, n) using of THERMOKINETICS software. The system can be described very accurately with a four-step kinetic model of consecutive reactions. On the basis of the kinetic model and parameters the realization of the first reaction step, which is the formation of the allophanate network is simulated. Finally, the result of the calculated progress of the reaction is evaluated by FT-IR and isothermal DSC measurements. 相似文献
64.
This work is part of an effort to develop chelating agents for stable binding and easy conjugation of Re-188 to biologically interesting structures. Starting from the well-known in vivo stability of [(188)ReO(DMSA)(2)](-), we want to exploit this coordination system for the design of (188)ReO(V) chelates, which are stable toward reoxidation to perrhenate and toward ligand exchange under all conditions of radiopharmaceutical development. Therefore, a new type of tetradentate ligand has been synthesized by bridging two molecules of N,N'-diisobutyl-2,3-dimercaptosuccinamide with N-(3-aminopropyl)propane-1,3-diamine. The resulting stereoisomeric tetrathiolato S(4) ligand of composition ((i)()Bu)(2)N(O)C-C(SH)-C(SH)-C(O)NH-(CH(2))(3)-NH-(CH(2))(3)-NHC(O)-C(SH)-C(SH)-C(O)N((i)Bu)(2) forms anionic five-coordinate oxorhenium(V) complexes by a ligand-exchange reaction of NBu(4)[ReOCl(4)] in methanol. In the absence of a base, the compounds were isolated as "betaine", [ReO(S(4))], with the protonated nitrogen of the bridge serving as an internal "counterion". Two representatives have been fully characterized in both the solid and solution states and found to adopt the expected square-pyramidal coordination geometry. The equatorial plane is formed by four thiolate sulfur atoms, whereas the oxygen occupies the apical position. The orientation of the metal oxo group is exo in relation to the carbamido groups in both isomers. Both complexes are stereoisomeric regarding the junction of the triamine chain. 相似文献
65.
The mechanism of dediazoniation of arenediazonium tetrafluoroborates in 2,2,2-trifluoroethanol (TFE) is strongly dependent on the concentration of added pyridine. The added base complexes with the diazonium ion and diverts it to a homolytic pathway. Complex formation is indicated by the disappearance of the \documentclass{article}\pagestyle{empty}\begin{document}$\raise1pt\hbox{---} \mathop {\rm N}\limits^ \oplus \equiv {\rm N}\raise1pt\hbox{---}$\end{document} stretching vibration and appearance of a new band at about 1640–1690 cm?1 ascribed to the \documentclass{article}\pagestyle{empty}\begin{document}$\raise1pt\hbox{---} {\rm N}\raise1pt\hbox{=\kern-3.45pt=} {\rm N}\raise1pt\hbox{---} \mathop {\rm N}\limits^ \oplus {\rm C}_5 {\rm H}_5$\end{document} system. UV. and NMR. results support this conclusion. Chemically induced dynamic nuclear polarization (CIDNP) experiments clearly implicate a radical-pair as an important intermediate in the decomposition of these complexes. 相似文献
66.
The detection of oxygen in magneto-optical layers is of fundamental importance for the characterization of the stability of RE-TM material. The magnetic properties are directly influenced by oxide formation. Oxygen depth profiles are carried out by using the SIMS technique. A comparison with magnetic measurements showed a clear conformity. We were able to study the oxidation behaviour of various layers at room temperature and at higher values up to 250° C for several hours. It could be shown that aluminum is a successful material for the protection of RE-films against oxidation. The difficulties of translating SIMS counting rates into concentration values were overcome by using EPMA. Specially prepared reference samples were measured by this technique and could then be used as standard samples for SIMS. 相似文献
67.
Heinrich Lang Bettina Lühmann Roy Buschbeck 《Journal of organometallic chemistry》2004,689(22):3598-3603
A straightforward method for the preparation of metallo carbosiloxanes of type Si(OCH2CH2CH2SiMe2[OCH2PPh2M(CO)n])4 (n = 3, M = Ni, 7a; n = 4, M = Fe, 7b; n = 5: M = Mo, 7c; M = W, 7d), Si(OCH2CH2CH2SiMe[OCH2PPh2Ni(CO)3]2)4 (8) and Me2Si(OCH2CH2CH2SiMe[OCH2PPh2Ni(CO)3]2)2 (11) is described. The reaction of Si(OCH2CH2CH2SiMeXCl)4 (1: X = Me, 2: X = Cl) or Me2Si(OCH2CH2CH2SiMeCl2)2 (9) with HOCH2PPh2 (3) produces Si(OCH2CH2CH2SiMe2(OCH2PPh2))4 (4), Si(OCH2CH2CH2SiMe(OCH2PPh2)2)4 (5) or Me2Si(OCH2CH2CH2SiMe(OCH2PPh2)2)2 (10) in presence of DABCO. Treatment of the latter molecules with Ni(CO)4 (6a), Fe2(CO)9 (6b), M(CO)5(Thf) (6c: M = Mo; 6d: M = W), respectively, gives the title compounds 7a-7d, 8 and 11 in which the PPh2 groups are datively bound to a 16-valence-electron metal carbonyl fragment.The formation of analytical pure and uniform branched and dendritic metallo carbosiloxanes is based on elemental analysis, and IR, 1H, 13C{1H}, 29Si{1H} and 31P{1H} NMR spectroscopic studies. In addition, ESI-TOF mass spectrometric studies were carried out. 相似文献
68.
The half-sandwich type compounds C5H5Rh[P(OR)3]2 (R = CH3, C2H5, C6H5, p-CH3C6H4, p-ClC6H4) have been prepared from [(P(OR)3)2RhCl]2 and NaC5H5. The NMR. data as well as the IR. and mass spectra of the new compounds will be discussed. The preparation of C5H5Rh(CO)P(OC2H5)3 is also reported. 相似文献
69.
70.
Siemeling U Bausch K Fink H Bruhn C Baldus M Angerstein B Plessow R Brockhinke A 《Dalton transactions (Cambridge, England : 2003)》2005,(14):2365-2374
The new diimine ligand 3,8-di-n-pentyl-4,7-di(phenylethynyl)-1,10-phenanthroline (1) was used for the synthesis of a range of Pt(II) complexes, viz.[Pt(1)Cl2], [Pt(1)(C triple bond C-Ph)2], [Pt(1)(C triple bond C-Fc)2] and [Pt(1)(C triple bond C-p-C6H4-C triple bond C-Fc)2](Fc = ferrocenyl). Crystal structure analyses were performed for [Pt(1)Cl2] and [Pt(1)(C triple bond C-Ph)2] and revealed that the di(acetylide)pi-tweezer of the latter binds a molecule of chloroform through C-H...pi hydrogen bonds. The redox and optical properties of 1 and its complexes were investigated by (spectro-)electrochemistry, UV-Vis and luminescence spectroscopy, and an energy level diagram was derived for [Pt(1)(C triple bond C-Fc)2] and related compounds on the basis of the data collected. The ferrocenyl-substituted Pt(II) complexes are donor-sensitiser assemblies. Intramolecular quenching of the photoexcited Pt(II) diimine unit leads to very short luminescence lifetimes for [Pt(1)(C triple bond C-p-C(6)H(4)-C triple bond C-Fc)2](2 ns) and [Pt(1)(C triple bond C-Fc)2](0.3 ns), as opposed to [Pt(1)(C triple bond C-Ph)2](0.7 micros). Excimer formation has been observed for [Pt(1)(C triple bond C-Ph)(2)] at room temperature in dichloromethane and at low temperatures in frozen glassy dichloromethane and 2-methyltetrahydrofuran solution, but not in the solid state. 相似文献