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991.
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
992.
Dong Han Kim 《Journal of heterocyclic chemistry》1976,13(6):1187-1192
1,2,3,4,8,9,10,11-Octahydro[1,4]diazepino[6,5,4-jk]earbazole (VIa) was synthesized from 2,3,4,5-tetrahydro-1H-benzodiazepine (la) via the route shown in Scheme 1. Other compounds which were prepared similarly are 3-acetyl-6-chloro-1,2,3,4,8,9,10,11-octahydro[1,4]diazepino-[6,5,4-jk]carbazole(Vb) and 3-methyl-1,2,3,4,8,9,10,11-octahydro[1,4]diazepino[6,5,4-jk]carb-azole (VIII). Chemical transformations which were carried out with VI and 3-acetyl-1,2,3,4,8,9, 10,11-octahydro[1,4]diazepino[6,5,4-jk]carbazole (Va) are also described. 相似文献
993.
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
994.
995.
The phosphorylation of piperidinomethylated dioxane lignin has been studied. It has been shown that the reaction takes place with the formation of quaternary ammonium phosphates, while the transesterification of dimethyl phosphite with an aliphatic hydroxy group of the lignin is also possible.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 275–277, March–April, 1993. 相似文献
996.
A. L. Nivorozhkin L. E. Konstantinovskii L. E. Nivorozhkin V. I. Minkin T. G. Takhirov O. A. D'yachenko D. B. Tagiev 《Russian Chemical Bulletin》1990,39(2):271-278
1H and13C NMR, x-ray structural analysis, and magnetic moment measurements have shown that in 5-thio(seleno)pyrazolealdiminate complexes of nickel(II) based on tetradentate ligands containing the fragment, with n=2, flattening of the chelate unit takes place in solution and in the solid state. A similar structure in which the diamine metal-containing ring has the twist-chair conformation is observed for the crystals of the complexes with n=4. For the complexes with n=4 in solution at a temperature below –50°C, rapid (on the NMR time scale) interconversion of the flattened (P) (S=0) and pseudotetrahedral (T) (S=1) structures is observed, not accompanied by inversion of the tetrahedral configuration of the metal atom. At temperatures above –50°C, in addition to the low-barrier reactions (T) (P), conversion of the seven-membered saturated metal-containing ring and inversion of the tetrahedral configuration of the Ni atom with activation barriers of 48–51 kJ/mole are observed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 327–335, February, 1990. 相似文献
997.
Stolarzewicz A Morejko-Buz B Neugebauer D 《Rapid communications in mass spectrometry : RCM》2000,14(23):2170-2174
Electrospray ionization mass spectrometry (ESI-MS) in positive- and negative-ion mode and multi-step tandem mass spectrometry (ESI-MS ( n) ) were selected for the determination of the structure of poly(methyl methacrylate) obtained using potassium hydride as initiator. Macromolecules with methoxy and methyl starting groups, i. e. those situated at the beginning of the polymer backbone, were observed in this case. No other differences in the chain structure were found in the polymer. 相似文献
998.
S. N. Tolstaja A. B. Taubman S. S. Mikhailova 《Journal of polymer science. Part A, Polymer chemistry》1978,16(11):2885-2892
The process of modifying the surface of particles of dispersed polymer fillers, using tensides, has been studied. The main principles were established with regard to the effect of modification of titanium dioxide and kaolin on the structure formation in solutions and block formations of chlorinated poly(vinyl chloride) resin and rubber, depending on the nature and concentration of the modifier. The decisive part played by chemisorption of the tenside in lyophilization (water-repellency treatment) of the surface of the filler and its activation, as a structure former, has been elucidated. 相似文献
999.
B. K. Rao N. R. Kestner J. A. Darsey 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,6(1):17-20
Detailed ab initio studies have been done on the inter-ring torsional states of the biphenyl molecule using self-consistent field molecular orbital method. The potential goes through a minimum at an angle of 38°. The height of the potential barrier for the coplanar state is 2.01 kcal/mol. When the phenyl rings are perpendicular to each other, this height increases to 2.37 kcal/mol. The role of correlation and polarization is found to be important. The shape of the potential suggests that polyparaphenylene may possibly exist as a super helix. 相似文献
1000.
Gallium-, Indium-Manganese-, and Thallium-Rhenium Carbonyl Compounds Compounds of type Na{Cl4?nM[Mn(CO)5]n} (M ? Ga, In; n = 1, 2, 3) were prepared by reaction of the Lewis acids MCl3 and NaMn(CO)5. Instead of the sodium salts were obtained the compounds (C3H7CO2)2InMn(CO)4L (Indium atom with the coordination number 5) from Indium(III) butyrate with two carboxylate groups bonded as chelate ligands and NaMn(CO)4L [L ? CO, P(C6H5)3] in the molar ratio 1:1. By reacting TlCl with NaRe(CO)5 i.r. spectroscopic measurements of the solution pointed out the intermediate product TlRe(CO)5, which was unstable against a disproportionation reaction into Tl and Tl[Re(CO)5]3. The last named compound delivered as a thermal decomposition product Re2(CO)8[μ-TlRe(CO)5]2. I.r. bands of the new compounds were assigned. 相似文献