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991.
Main aspects of the activity of the outstanding Ukrainian analyst A.K. Babko are considered.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 2, 2005, pp. 211–213.Original Russian Text Copyright © 2005 by Shtokalo.This revised version was published online in April 2005 with corrections to the author names and book review format.  相似文献   
992.
Ten unsymmetrically substituted arylamino-1,3,5-triazines were synthesized and studied by dynamic NMR spectroscopy. The free energies of the hindered rotation ΔG?are in 59–77 kJ mol? 1 range. Using difference-mode NOE NMR experiments, the structures of the major and minor rotation isomers were proved. The DFT B3LYP/6-31G* calculations were performed. The difference between the calculated rotation barriers and the experimental values obtained by line shape analysis is less than 7.6 kJ mol?1. The height of the rotation barrier varies in a 18 kJ mol?1 range depending on the substituents in the triazine ring.  相似文献   
993.
3-(2-Benzimidazolyl)-4-hydroxy-2-quinolone was unexpectedly obtained as the principal reaction product on fusion of 2-carbethoxymethyl-4H-3,1-benzoxazin-4-one with o-phenylenediamine. A possible mechanism of its formation is presented.For Communication 2 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 239–241, February, 1992.  相似文献   
994.
Summary A survey of the authors' work on liquid chromatography of platinum metals in the form of chelates with 1-(2-pyridylazo)-2-naphthol (PAN) is given. Extraction chromatography with PAN in isopentanol as a stationary phase was used to achieve a group concentration of these metals (Pd, Pt and Rh, concentration coefficient 100) from large volumes of aqueous solutions and a selective extraction of palladium from solutions containing other platinum, nonferrous and heavy metals on a 85–98° C thermostatted chromatographic column. The prospects for the use of liquid chromatography in the analysis of platinum metals are discussed.
Flüssig-Chromatographie von Platinmetallen und zukünftige Entwicklungen
  相似文献   
995.
The effects of the nature of the metal atom and -substituents in aluminum(III), chromium(III), cobalt(III), and iron(III) acetylacetonates on the lifetime and intensity of a long-lived component in positron and positronium annihilation were studied by the method of positron diagnostics. An addition of a positron to the -system of a chelate ring is supposed, which makes it possible to qualitatively estimate the basicities of the complexes. Annihilation of positrons and halogen-containing positronium -diketonates is accompanied by the formation of a protonated complex; for -organylthioacetylacetonates, annihilation follows the inhibition mechanism.  相似文献   
996.
Procedures for synthesis of coordination compounds of copper(II) with bis(5-amino-1,2,4-triazol-3-yl)alkanes as ligands. A conclusion was drawn that the coordination polyhedron of copper(II) has different configurations depending on the structure of the ligand and on the coordination mode.  相似文献   
997.
Weak interactions of nonaromatic amino acids with - and -cyclodextrins in aqueous solutions at 298.15 K were studied calorimetrically. The structure and solvation of these compounds noticeably affect the thermodynamic characteristics of interparticle interactions.  相似文献   
998.
Combined methods for the determination of noble metals with the use of sorption preconcentration with complexing, anion-exchange, and other sorbents are reviewed. Characteristics of sorbents, techniques of sorption preconcentration, and techniques for the preparation of a concentrate for determination are considered. Features of instrumental methods for the determination of noble metals in the analysis of different materials are discussed. Examples of the use of sorption preconcentration in combined methods for the determination of noble metals are given from publications between 1996–2005.  相似文献   
999.
The crystal and molecular structures of bis(1-isopropenylimidazole)dichlorocobalt (C12H16Cl2·N4Co) [R 0.036 (R W 0.089) for 3229 unique reflections with I > 2σ(I)] and tetra(1-vinylimidazole)dichlorocobalt (C20H24Cl2N8Co) [R 0.031 (R W 0.072) for 1863 unique reflections with I > 2σ(I)] were determined. In these molecular complexes, the monodentate terminal 1-alkenylimidazole ligands coordinate to the metal via a “pyridine” nitrogen atom. In C12H16Cl2N4Co, the Co atom has a distorted tetrahedral 2N,2Cl coordination. The coordination polyhedron of cobalt in C20H24Cl2N8Co is a strongly elongated 4N,2Cl octahedron. The Co-N and Co-Cl bonds [Co-N 2.015(2) and 2.032(4) Å; Co-Cl 2.229(2) Å] in the tetrahedral complex C12H16Cl2N4Co are shorter than those in the octahedral complex C20H24Cl2N8Co [Co-N 2.134(2) and 2.157(2) Å; Co-Cl 2.518(1) Å]. In the structures of both complexes there are short contacts involving the Cl atoms.  相似文献   
1000.
Nitropyrazoles     
The double Vilsmeier formylation of theC-methyl group in pyrazole derivatives has been shown to occur when a nitro-group is in the adjacent position of the ring. A method for the synthesis ofC-(diformylmethyl)nitropyrazoles based on this reaction has been developed.For the previous communication, see Ref. 1; for Part 2, see Ref.2 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1273–1276, July, 1993.  相似文献   
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