Summary Complexes of cobalt(II), nickel(II) and copper(II) with novel bidentate bibenzimidazoles, [M(L-L)Cl2], where L-L are methylenebis(1, 1-benzimidazole), methylenebis(2, 2-benzimidazole) and dimethylenebis(2, 2-benzimidazole) are described and characterized by different physical measurements. The four coordinate complexes have distorted tetrahedral or square coplanar structures. The bridging entity between the two donor groups apparently influences the ligand field strength and the ligands occupy a higher position than that of benzimidazole in the spectrochemical series. 相似文献
Reaction of N-(2,4-dinitrophenyl)-C-alkyl hydrazonyl chlorides with diverse dipolarophiles gave a variety of novel heterocyclics, which are expected to possess biological activities. The ring closure is brought about by a concerted process involving nitrile imine as an intermediate. The structures of the resulting products are supported by nmr and ir spectral data. 相似文献
Theoretical analysis of kinetic data obtained under increasing temperature conditions requires the solution of an exponential integral through various approximations. This paper shows that some common types of temperature variation approximating linear variation can be described, at least in limited temperature ranges, by a reciprocal temperature rise equation of the kind where T is the absolute temperature, t is time and a and b are constants. Use of this equation leads directly to a simple and exact solution. A set of actual experimental data on the decomposition of CaCO3 is analyzed to substantiate the approach proposed and demonstrate its usefulness. 相似文献
The kinetics of formation of charge transfer complexes of poly(4-vinyl pyridine), poly(2-vinyl pyridine), and poly(2-vinyl pyridine-co-styrene) with iodine, 7,7′,8,8′-tetracyanoquinodimethane and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone has been studied using electronic absorption spectroscopy. The charge transfer complexes of analogous low molecular weight donors, namely 2- and 4-picolines with the same set of acceptors have also been investigated for comparison. The composition and the equilibrium constants of the charge transfer complexes have been obtained. The equilibrium constant of the polymeric complexes is found to be higher than that of analogous complexes of the low molecular weight donors. A new method for determining the rate constants of the association and dissociation of the equilibrium involving the charge transfer complex formation has been proposed. The rate constants vary with the concentration of the acceptor. It indicates that the charge transfer complexes undergo a further reaction and hence the observed rate constants are not true but apparent rate constants. The charge transfer complexes have also been investigated by electron paramagnetic resonance spectroscopy. 相似文献
The extraction of In(III) from HCl, H2SO4, and HNO3 media using a 0.20 mol l−1 Cyanex 923 solution in toluene is investigated. In(III) is quantitatively extracted over a fairly wide range of HCl molarity while from H2SO4 and HNO3 media the extraction is quantitative at low acid concentration. The extracted metal ion has been recovered by stripping with 1.0 mol l−1 H2SO4. The stoichiometry of the In(III): Cyanex 923 complex is observed to be 1:2. The extraction of In(III) is insignificantly changed in diluents namely toluene, n-hexane, kerosene (160-200 °C), cyclohexane, and xylene having more or less the same dielectric constants, whereas, it decreases with increasing polarity of diluents such as cyclohexanone and chloroform. The extractant is stable towards prolonged acid contact and there is a negligible loss in its extraction efficiency even after recycling for 20 times. The extraction behavior of some commonly associated metal ions namely V(IV), Ti(IV), Al(III), Cr(III), Fe(III), Ga(III), Sb(III), Tl(III), Mn(II), Fe(II), Cu(II), Zn(II), Cd(II), Pb(II), and Tl(I) has also been investigated. Based on the partition data the conditions have been identified for attaining some binary separations of In(III). These conditions are extended for the recovery of pure indium from zinc blend, zinc plating mud, and galena. The recovery of the metal ions is around 95% with purity approximately 99%. 相似文献
Sodium bis(trimethylstannyl)amide NaN(SnMe3)2, isolated by the reaction of trimethylstannyldiethylamine with sodium amide, reacts with tris(trimethylsilyl)hydrazino—dichloro-phosphine to form bis(trimethylsilyl)bis(trimethylstannyl)-2-phospha-2-tetrazene, (Me3Si)2N-N=P-N(SnMe3)2. Both the molecules have been isolated and characterized. 相似文献
Summary An X-ray fluorescence method for the analysis of calcium in uranium in the range of 20 to 500 ppm is described. U3O8 samples are mixed with boric acid binder and double-layer pellets are prepared. The pellets are analysed using Philips PW 1220 semi-automatic X-ray spectrometer. Calculated lower limits of detection are better than 5 ppm for calcium in uranium.
Bestimmung von Calcium in Uran durch Röntgenfluorescenz
Zusammenfassung Ein Verfahren für den Bereich von 20–500 ppm wird beschrieben. Die U3O8-Proben werden mit BorsÄure als Bindemittel vermischt zu Doppelschicht-Tabletten gepre\t, die mit Hilfe eines halbautomatischen Philips PW 1220 Röntgenspektrometers analysiert werden. Die untere Nachweisgrenze liegt bei 5 ppm Ca.