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排序方式: 共有210条查询结果,搜索用时 15 毫秒
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Aleksandr V. Prichodko Evgenii V. Shatkovski Sergei G. Yastrebov 《International Journal of Infrared and Millimeter Waves》1994,15(3):579-584
Photostimulated changes in thin carbon films deposited onto fused silica substrates by reactive magnetron sputtering and irradiated by the light of the first (1060nm) and the second (530nm) harmonics of a QW-switched Nd3+ AVG laser were investigated. The changes are supposed to be connected with the reordering of chemical bounds. 相似文献
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Konstantin P Bryliakov Nina V Semikolenova Vladimir A Zakharov Martin Ystenes Evgenii P Talsi 《Journal of organometallic chemistry》2003,683(1):92-102
Using 1H- and 13C-NMR spectroscopies, cationic intermediates formed by activation of L2ZrCl2 with methylaluminoxane (MAO) in toluene were monitored at Al/Zr ratios from 50 to 1000 (L2 are various cyclopentadienyl (Cp), indenyl (Ind) and fluorenyl (Flu) ligands). The following catalysts were studied: (Cp-R)2ZrCl2 (R=Me, 1,2-Me2, 1,2,3-Me3, 1,2,4-Me3, Me4, Me5, n-Bu, t-Bu), rac-ethanediyl(Ind)2ZrCl2, rac-Me2Si(Ind)2ZrCl2, rac-Me2Si(1-Ind-2-Me)2ZrCl2, rac-ethanediyl(1-Ind-4,5,6,7-H4)2ZrCl2, (Ind-2-Me)2ZrCl2, Me2C(Cp)(Flu)ZrCl2, Me2C(Cp-3-Me)(Flu)ZrCl2 and Me2Si(Flu)2ZrCl2. Correlations between spectroscopic and ethene polymerization data for catalysts (Cp-R)2ZrCl2/MAO (R=H, Me, 1,2-Me2, 1,2,3-Me3, 1,2,4-Me3, Me4, Me5, n-Bu, t-Bu) and rac-Me2Si(Ind)2ZrCl2 were established. The catalysts (Cp-R)2ZrCl2/AlMe3/CPh3+B(C6F5)4− (R=Me, 1,2-Me2, 1,2,3-Me3, 1,2,4-Me3, Me4, n-Bu, t-Bu) were also studied for comparison of spectroscopic and polymerization data with MAO-based systems. Complexes of type (Cp-R)2ZrMe+←Me−-Al≡MAO (IV) with different [Me-MAO]− counteranions have been identified in the (Cp-R)2ZrCl2/MAO (R=n-Bu, t-Bu) systems at low Al/Zr ratios (50-200). At Al/Zr ratios of 500-1000, the complex [L2Zr(μ-Me)2AlMe2]+[Me-MAO]− (III) dominates in all MAO-based reaction systems studied. Ethene polymerization activity strongly depends on the Al/Zr ratio (Al/Zr=200-1000) for the systems (Cp-R)2ZrCl2/MAO (R=H, Me, n-Bu, t-Bu), while it is virtually constant in the same range of Al/Zr ratios for the catalytic systems (Cp-R)2ZrCl2/MAO (R=1,2-Me2, 1,2,3-Me3, 1,2,4-Me3, Me4) and rac-Me2Si(Ind)2ZrCl2/MAO. The data obtained are interpreted on assumption that complex III is the main precursor of the active centers of polymerization in MAO-based systems. 相似文献
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Elena S. Osipova Ekaterina S. Gulyaeva Evgenii I. Gutsul Vladislava A. Kirkina Alexander A. Pavlov Yulia V. Nelyubina Andrea Rossin Maurizio Peruzzini Lina M. Epstein Natalia V. Belkova Oleg A. Filippov Elena S. Shubina 《Chemical science》2021,12(10):3682
The reaction between basic [(PCP)Pd(H)] (PCP = 2,6-(CH2P(t-C4H9)2)2C6H4) and acidic [LWH(CO)3] (L = Cp (1a), Tp (1b); Cp = η5-cyclopentadienyl, Tp = κ3-hydridotris(pyrazolyl)borate) leads to the formation of bimolecular complexes [LW(CO)2(μ-CO)⋯Pd(PCP)] (4a, 4b), which catalyze amine-borane (Me2NHBH3, tBuNH2BH3) dehydrogenation. The combination of variable-temperature (1H, 31P{1H}, 11B NMR and IR) spectroscopies and computational (ωB97XD/def2-TZVP) studies reveal the formation of an η1-borane complex [(PCP)Pd(Me2NHBH3)]+[LW(CO3)]− (5) in the first step, where a BH bond strongly binds palladium and an amine group is hydrogen-bonded to tungsten. The subsequent intracomplex proton transfer is the rate-determining step, followed by an almost barrierless hydride transfer. Bimetallic species 4 are easily regenerated through hydrogen evolution in the reaction between two hydrides.Bimetallic complexes [LW(CO)2(μ-CO)⋯Pd(PCP)] cooperatively activate amine-boranes for their dehydrogenation via N–H proton tunneling at RDS and H2 evolution from two neutral hydrides. 相似文献
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Hybrid Silsesquioxane/Benzoate Cu7-Complexes: Synthesis,Unique Cage Structure,and Catalytic Activity
Alexey N. Bilyachenko Victor N. Khrustalev Evgenii I. Gutsul Anna Y. Zueva Alexander A. Korlyukov Lidia S. Shulpina Nikolay S. Ikonnikov Pavel V. Dorovatovskii Dmitri Gelman Elena S. Shubina Georgiy B. Shulpin 《Molecules (Basel, Switzerland)》2022,27(23)
A series of phenylsilsesquioxane-benzoate heptacopper complexes 1–3 were synthesized and characterized by X-ray crystallography. Two parallel routes of toluene spontaneous oxidation (into benzyl alcohol and benzoate) assisted the formation of the cagelike structure 1. A unique multi-ligation of copper ions (from (i) silsesquioxane, (ii) benzoate, (iii) benzyl alcohol, (iv) pyridine, (v) dimethyl-formamide and (vi) water ligands) was found in 1. Directed self-assembly using benzoic acid as a reactant afforded complexes 2–3 with the same main structural features as for 1, namely heptanuclear core coordinated by (i) two distorted pentameric cyclic silsesquioxane and (ii) four benzoate ligands, but featuring other solvate surroundings. Complex 3 was evaluated as a catalyst for the oxidation of alkanes to alkyl hydroperoxides and alcohols to ketones with hydrogen peroxide and tert-butyl hydroperoxide, respectively, at 50 °C in acetonitrile. The maximum yield of cyclohexane oxidation products as high as 32% was attained. The oxidation reaction results in a mixture of cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone. Upon the addition of triphenylphosphine, the cyclohexyl hydroperoxide is completely converted to cyclohexanol. The specific regio- and chemoselectivity in the oxidation of n-heptane and methylcyclohexane, respectively, indicate the involvement of of hydroxyl radicals. Complex 3 exhibits a high activity in the oxidation of alcohols. 相似文献
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Galina A. Gazieva Yurii B. Vikharev Lada V. Anikina Tatyana B. Karpova Angelina N. Kravchenko Evgenii A. Permyakov Igor V. Svitanko 《Mendeleev Communications》2013,23(4):202-203
Target synthesis of substituted thioglycolurils possessing sedative activity predicted by preliminary 3D-QSAR simulation of bioactive structures has been carried out. 相似文献
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The drive belt set on two pulleys is considered as a plane elastic rod. The nonlinear theory of rods with tension is used. The static frictionless contact problem for the rod is formulated. The derived boundary value problem for the nonlinear ordinary differential equations is solved by the finite difference method and by the shooting method by means of computer mathematics. The belt shape and the stresses are determined. The contact reaction and the contact area are obtained in the solution. A benchmark study of extensible and inextensible models is performed. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献