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981.
The synthesis, characterization, and incorporation in volatile metal-organic chemical vapor deposition (MOCVD) precursors of a new class of linked beta-ketoiminate-polyether-beta-ketoiminate ligands is presented. These ligands are designed to encapsulate alkaline-earth cations having low charges and large ionic radii. Barium complexes having the general formula Ba[(RCOCHC(R')N)2(R")] (R = tert-butyl or CF3; R' = tert-butyl, methyl, or CF3; R" = -(CH2CH2O)4CH2CH2- or -(CH2CH2O)5CH2CH2)-) were prepared and characterized by 1H and 13C NMR spectroscopy, elemental analysis, and mass spectrometry. Single-crystal X-ray diffraction analysis of 2,2,5,25,28,28-hexamethyl-9,12,15,18,21-pentaoxa-4,25-diene-6,24- diimino-3,27-pentacosadionatobarium(II) reveals a monomeric, nine-coordinate, tricapped trigonal prismatic coordination geometry. Single-crystal X-ray structural analysis of 1,1,1,24,24,24-hexafluoro-4,21-ditrifluoromethyl-8,11,14,17- tetraoxa-3,21-diene-5,20-diimino-2,23-tetracosadionatobarium(II).2DMSO reveals a monomeric, ten-coordinate, distorted tetracapped trigonal prismatic coordination geometry. Volatility data are presented for these barium complexes, demonstrating viability as MOCVD precursors. In addition, it is demonstrated that thin epitaxial films of BaTiO3 can be grown on (001) MgO by low-pressure MOCVD techniques using one of these barium complexes and Ti(dipivaloylmethanate)2(isopropoxide)2 as precursors. 相似文献
982.
We have developed a simple and physically clear picture of adiabatic rapid passage (ARP) in molecules in solution by careful examination of all the conditions needed for ARP. The relaxation effects were considered in the framework of the Landau-Zener model for random crossing of levels. The model enables us to include into consideration non-Markovian Gaussian-correlated noise. It explains all the numerical results obtained in the first paper of the series [B. D. Fainberg and V. A. Gorbunov, J. Chem. Phys. 117, 7222 (2002)], in particular, that for positive chirp pulse excitation relaxation favors more efficient population transfer with respect to the relaxation-free system with frozen nuclear motion. We also relate parameters of non-Markovian Gaussian-correlated noise with irreversible dephasing time of an optical transition by calculating the photon echo signal attenuation. 相似文献
983.
A general synthesis has been achieved to obtain carcinogen modified quanosines. The method was applied to the preparation of the N- 2, 5-diamino-4-oxo-3H-pyrimidine-6-yl-N-(β-D-ribofuranosyl)-N(2-fluorenyl)urea . 相似文献
984.
An analysis has been made of the conformations of the 10-membered ring in the known sesquiterpene E,E-germacranes and a relationship has been established between the realization of one of the four conformers and the positions and orientations of substituents in the 10-membered ring. A relationship is presented between the conformational states of the germacrolides and the structures of their bicyclic derivatives — guaianes and eudesmanes.Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 497–506, July–August, 1997. 相似文献
985.
E. S. Klimov F. Kim V. Kh. Sabanov T. I. Chulkova O. Yu. Okhlobystin 《Theoretical and Experimental Chemistry》1992,28(1):58-60
1,8-Naphthylenediamine was reacted with 2,6-di-tert-butyl-4-formyl-phenol to produce 2,6-di-tert-butyl-4-(1,3-dihydro-perimidyl) phenol (I). The latter was coverted into 2,6-di-tert-butyl-4-(1H-perimidyl)phenol (II) by oxidizing I with sodium pyrosulfate. When phenol II was oxidized by lead dioxide in toluene and THF, the EPR spectra revealed a 12-component multiplet with perimidyl splitting constants a1
N=a3
N=aH
NH=0.2 mT; aH
6.7=0.6 mT.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 1, pp. 64–67, January, 1992. 相似文献
986.
I. Belič T. Kastelic-Suhadolc R. Kavčič J. Marsel V. Kramer B. Kralj 《Tetrahedron》1976,32(24):3045-3049
The oxidation of higher aliphatic ethers with oxygen at 50° yields two peroxides as the main oxidation products for each ether, namely a dihydroperoxy-dialkyl ether and a dihydroperoxy-dialkyl peroxide. The mass spectra of these compounds are recorded and the main fragmentation pattern is discussed. 相似文献
987.
K.B. Starowieyski S. Pasynkiewicz A. Sporzyński 《Journal of organometallic chemistry》1976,117(2):117-128
Reasonably stable 1 : 2 complexes are formed by carbonyl compounds with chloroaluminium compounds, usually in equilibrium with a 1: 1 complex, however with trimethylaluminium only a 1 : 1 complex is formed. In the case of complexes with an excess of MeAlCl2, a disproportionation reaction occurs. Possible structures are discussed in light of PMR and IR spectroscopy, dipole moments and molecular weight determination. The previously proposed cyclic six-membered ring is the most reliable structure for the 1 : 2 complex. 相似文献
988.
E Wenkert E W Hagaman B Lal G E Gutowski A S Katner J C Miller N Neuss 《Helvetica chimica acta》1975,58(6):1560-1567
The total assignment of the 13C-shifts of the complex Vinica rosea L. alkaloids vincaleucoblastine, leurosidine and leurosine and of a synthetic isomer of the latter is presented. The structure of leurosidine is corrected and a tentative structure for the acid-catalyzed product of isomerization of leurosine is proposed. 相似文献
989.
990.
I. V. Shkutina O. F. Stoyanova V. F. Selemenev 《Russian Journal of Applied Chemistry》2005,78(6):981-984
Some fundamental aspects of the immobilization of a hydrolytic enzyme glucoamylase via adsorption on aminocarboxylic ion-exchangers with fibrous structure were considered. The sorption capacity of amphoteric supports for the enzyme was studied in relation to the time of immobilization, concentration of hydrogen ions and the protein, and the ionic form of a polyelectrolyte. The catalytic properties of free and immobilized enzymes were compared.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005, pp. 1003–1005.Original Russian Text Copyright © 2005 by Shkutina, Stoyanova, Selemenev. 相似文献