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281.
Trávníček Zdeněk Walla Jan Kvítek Libor Šindelář Zdeněk Biler Martin 《Transition Metal Chemistry》1999,24(6):633-637
Nickel(II) xanthate complexes of general formula, [Ni(Rxa)2(L)] [R = i-Pr, i-Am, xa = OCS–
2, L = 4,7-diphenyl-1,10-phenanthroline(baphen), 4,4-dimethyl-2,2-bipyridyl (me2bpy), 2-9-dimethyl-1,10-phenanthroline(neo) or trans-1,2-diaminocyclohexane (dch)] and [Ni(Rxa)(cyclam)](Rxa) (= 1,4,8,11-tetraazacyclotetradecane) have been synthesized and characterized by elemental analyses, i.r. and electronic spectroscopy, magnetic and conductivity measurements. The complexes with cyclam were studied by cyclic voltammetry. Values of magnetic moments at room temperature lie within the 3.25–3.51 B.M. range and thus indicate the presence of two unpaired electrons, except for the complexes with cyclam, where the anomalous values of 1.76 and 1.74 B.M. were obtained in respect to the nickel(II) complexes. Magnetic susceptibility data for [Ni(i-Prxa)(cyclam)](i-Prxa) were measured over the 79–298 K range and indicate no exchange interaction between paramagnetic nickel(II) centres. 相似文献
282.
Zusammenfassung Es werden zwei neue Wege zur herstellung des 4,4-Äthinylendiphenols beschrieben. Der erste beruht auf der Entmethylierung des Bis-(4-methoxyphenyl)acetylens, der zweite auf der Oxydation des 4,4-Dihydroxybenzildihydrazons nach derCurtiusschen Methode.
Two new syntheses of 4.4-ethynylene diphenol
Two new syntheses of 4.4-ethynylene diphenol are described: demethylation of bis-(4-methoxyphenyl)-acetylene, and oxidation of 4.4-dihydroxybenzildihydrazone according toCurtius.相似文献
283.
Summary This paper presents a continuation of our research dedicated to solid-adsorbent surface modification with what are commonly regarded as volatile and easily eluted organic compounds. Two porous adsorbents were used: natural zeolite (clinoptilolite) and alumina, while the adsorbates employed were n-hepatane and benzene. The results show that a simple injection of volatile adsorbate greatly alters the solid surface adsorption properties. The consequences of volatile modifier application are discussed on the grounds of adsorption isotherms determined at 313K. Possible implications to the tailor made adsorbents are outlined as well.Part I, J. Chromatogr.442, 105 (1988) 相似文献
284.
Vladimír Kvasnička 《Chemical physics letters》1976,43(2):377-381
A second-quantization representation of the Epstein-Nesbet partitioning of the total electronic hamiltonian is suggested. In this approach, the unperturbed hamiltonian contains not only the one-particle orbital energies but also the Coulomb and corresponding exchange two-particle terms. Such a hamiltonian can advantageously be used in all branches of the many-body diagrammatic perturbation theory for simple and correct inclusion of the diagonal ladder and ring diagrams in all orders of perturbation theory. 相似文献
285.
M. Katkevičs A. Kontijevskis I. Mutule E. Sūna 《Chemistry of Heterocyclic Compounds》2007,43(2):151-159
A 30-membered library of coumarins has been synthesized in a microwave-assisted Pechmann reaction using neat trifluoroacetic
acid both as an acidic reagent and a reaction medium. Alternatively, polymer-supported sulfonic acid Amberlyst-15 could also
be employed to facilitate the formation of coumarins. The use of a specially-built microwave synthesizer with liquid handling
tools rendered the automated synthesis of a coumarin library feasible.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 200–208, February, 2007. 相似文献
286.
I. B. Plećaš A. D. Perić J. D. Drljača A. M. Kostadinović 《Journal of Radioanalytical and Nuclear Chemistry》1992,157(1):95-104
An optimization of mortar (as matrix), improved with bentonite clay, used for immobilization of radionuclides60Co,137Cs,85Sr and54Mn, is presented. A relatively simple mathematical model is given, which permits minimization of leach rate and permeability and maximization of compressive strength. An optimal solution, based on experimental data, is given. These results will be used for a future Yugoslav radioactive waste storing center. 相似文献
287.
106Ru chloro and nitrosyl-nitrato complexes in sea water were separated into several species by continuous electrophoresis on
a filter paper curtain. Biological uptake experiments were carried out on sea algae Fucus virsoides with fractionated106Ru chloro and nitrosyl-nitrato complex species in sea water. The biological uptake of106Ru chloro complex species was about 8 times higher than the uptake of106Ru nitrosyl-nitrato species. Electrophoretically most mobile electrically positively charged cationic species in both systems
also showed about 8 times higher biological uptake than the most mobile negatively charged anionic species. A close relation
of the biological uptake to the sign of the electrical charge and the electrophoretic mobility of the species is demonstrated.
The results are discussed with respect to possible danger to the biological environment as a consequence of the aging of ruthenium
species in sea water resulting from106Ru waste disposal to the sea from a nuclear reprocessing plant.
On leave of absence from the National Institute of Radiological Sciences, 9-1, 4-chome, Anagawa, Chiba-shi, Japan, on a fellowship
from The Science and Technology Agency of the Japanese Govemment. 相似文献
288.
G. Mekuškiené P. Vainilavičius A. Hetzheim R. Shematovich 《Chemistry of Heterocyclic Compounds》1993,29(5):598-602
The reaction of the hydrazide of 4,6-dimethyl-2-pyrimidinecarboxylic acid with potassium ethylxnthate gave 5-(4,6-dimethyl-2-pyrimidinyl)-1,3,4-oxadiazole-2-thione. The alkylation of this product in an alkaline medium proceeds at the sulfur atom, while the aminomethylation and acylation proceed at the nitrogen atom. The major criterion for the structure of the S- and N-derivatives is the chemical shift of C(2) in the 1,3,4-oxadiazole ring in the 13C NMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 700–705, May, 1993. 相似文献
289.
Zusammenfassung 1,3-Dimethyl-4,5-diaminouracil (DAL) hat sich als sehr empfindliches Reagens zum selektiven Nachweis von Co2+-Ionen im stark alkalischen Medium einer Phosphatpufferlösung (pH=11,20) erwiesen. Es wurden vier Additionsverbindungen von DAL mit den Zentralatomen Cd(II), Pd(II), Ni(II) und Co(II) im Verhältnis Me DAL=1 2 hergestellt. Spektrophotometrische Untersuchungen weisen darauf hin, daß bei pH 6 bis 7 eine Komplexverbindung im Verhältnis CoDAL=12 gebildet wird.
Summary 1,3-dimethyl-4,5-diaminouracil (DAL) has been found to be a very sensitive reagent for the selective detection of Co2+ ions in strong alkaline medium of a phosphate buffer solution (pH=11.20). Four addition compounds of DAL with the central atoms Cd(II), Pd(II), Ni(II) and Co(II) with the ratio MeDal=12 have been prepared. Spectrophotometric studies indicate that at pH=6–7, complex compound is produced with the ratio CoDAL=12.相似文献
290.
M. Hampl J. Leitner K. Růžička M. Straka P. Svoboda 《Journal of Thermal Analysis and Calorimetry》2007,87(2):553-556
The heat capacity and the heat content of
bismuth niobate BiNb5O14 were
measured by the relaxation time method, DSC and drop method, respectively.
The temperature dependence of heat capacity in the form C
pm=455.84+0.06016T–7.7342·106/T
2 (J K–1
mol–1) was derived by the least squares method
from the experimental data. Furthermore, the standard molar entropy at 298.15
K S
m=397.17 J K–1
mol–1 was derived from the low temperature
heat capacity measurement. 相似文献