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801.
Gnanasoundari Vettaikaranpudur G. Natarajan Karuppannan 《Transition Metal Chemistry》2004,29(5):511-515
A series of new Schiff base complexes of FeIII, CoII, NiII and CuII containing Ph3P has been prepared and characterised. The Schiff bases have been prepared by the condensation of salicylaldehyde and naphthaldehyde with the appropriate aniline. The complexes have been characterised by analytical, spectral (i.r., electronic, magnetic, e.p.r., 1H-n.m.r.) and electrochemical studies. The new complexes have been used as catalysts for aromatic coupling reactions. Higher catalytic activity has been observed for NiII compared to the other complexes. 相似文献
802.
C. V. Karekar Keshav Chander G. M. Nair P. R. Natarajan 《Journal of Radioanalytical and Nuclear Chemistry》1986,107(5):297-305
A potentiometric titration method was developed for the determination of plutonium and uranium in the same aliquot in nitric acid medium. Plutonium was first determined by oxidation to Pu/VI/ by fuming with conc. HClO4. Pu/VI/ formed was reduced to Pu/IV/ with known excess of Fe/II/ and the excess Fe/II/ was titrated with standard K2Cr2O7 to a potentiometric end point. Uranium in the same solution was determined by reduction to U/IV/ with Fe/II/ in conc. H3PO4 medium and titrating U/IV/ formed with standard K2Cr2O7 using the potentiometric end point detection technique. For the quantity of plutonium and uranium each in the range of 3–5 mg per aliquot a precision of ±0.2% and ±0.4%, respectively, was obtained. 相似文献
803.
Two new alkali metal borophosphates, K3[BP3O9(OH)3] and Rb3[B2P3O11(OH)2], were synthesized by applying solvothermal techniques using ethanol as solvent. The crystal structures were solved by means of single-crystal X-ray diffraction (K3[BP3O9(OH)3], monoclinic, C2/c (No. 15), a = 2454.6(8) pm, b = 736.3(2) pm, c = 1406.2(4) pm, beta = 118.35(2) degrees , Z = 8; Rb3[B2P3O11(OH)2], monoclinic, P2(1)/c (No. 14), a = 781.6(2) pm, b = 667.3(2) pm, c = 2424.8(5) pm, beta = 92.88(1) degrees , Z = 4). Both crystal structures comprise borophosphate chain anions. While for the rubidium compound a loop-branched chain motif is found as common for most of the chain anions in alkali metal borophosphates, the crystal structure of the potassium phase comprises the first open-branched chain with the highest phosphate content found so far in this group of compounds. Both chain anions are closely related to known anhydrous or hydrated phases, and the structural relations are discussed in terms of how the presence of OH groups and hydrogen bonds as well as number, charge, and size of charge balancing cations influence the 3D structural arrangement. The anionic entities are classified in terms of general principles of structural systematics for borophosphates. 相似文献
804.
The oxidation by Br(V) of propan-2-ol follows the rate law (?d[Br(V)]/dt) = k4 [alcohol][Br(V)][H+]2. The initial reaction is complicated by the presence of the product bromide ion. The reaction is composed of two second order reactions—the first, a comparatively slow one and the second stage, a faster reaction which is mainly bromine oxidation. The pure bromate oxidation can be followed by the initial addition of mercuric acetate which prevents the accumulation of bromine in the system under these conditions. The reaction rate does not depend on the nature and structure of the alcohol. A mechanism involving a slow rate-determining formation of an alkyl-bromate ester followed by a fast decomposition to the products is in accord with the observed results. 相似文献
805.
Summary Complexes of furan and thiophene azo-oximes with iron(II), cobalt(III), nickel(II) and copper(II) have been prepared and characterised. Iron(II), cobalt(III) and copper(II) complexes are diamagnetic in the solid state. The diamagnetism of the copper(II) chelates is suggestive of antiferromagnetic interaction between two copper centres.1H n.m.r. spectral data suggest atrans-octahedral geometry for the tris-chelates of cobalt(III). Nickel(II) complexes are paramagnetic, in contrast to the diamagnetism of the analogous complexes of arylazooximes. The electronic spectra are suggestive of octahedral geometry for the iron(II), cobalt(III) and nickel(II) complexes, andD
4h
-symmetry for copper(II). Infrared data indicate N-bonding of the oximino-group to the metal ions. 相似文献
806.
R. Chidambaram M.K. Sanyal P.M.G. Nambissan P. Sen 《Progress in Crystal Growth and Characterization of Materials》1997,34(1-4):207-220
We discuss implications of our results of positron annihilation studies of various icosahedral quasicrystalline alloys on the structural models of this new phase. We have studied Al-Mn, Al-Mn-Si, Al-Cu-Li and Al-Cu-Fe and a two component positron annihilation lifetime spectrum seems characteristics of all these icosahedral quasicrystalline alloy phases. Analysis of the lifetime spectra yields vacancy sizes varying from monovacancies to hexavacancies with concentration of 1 to 8 ppm in various quasicrystalline alloys. These vacancy concentrations are about three orders of magnitude less than that observed in metallic glasses. We also notice that in the case of metastable quasicrystalline alloys such as Al-Mn and Al-Mn-Si, these vacancy clusters disappear during the crystallization process resulting in single lifetime spectra. On the other hand, for stable quasicrystalline alloys, two component life time spectra, which indicate the presence of vacancy clusters, continue to exist even after prolonged heat treatment. Our results seem incompatible with the space filling Penrose tiling or random tiling models and favour cluster-based models. 相似文献
807.
808.
V. Natarajan B. Rajeswari B. A. Dhawale N. S. Hon S. V. Godbole V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(1):27-31
Energy dispersive X-ray fluorescence (EDXRF) spectrometric methods have been developed for the determination of some common
metallic impurities in ThO2 matrix. A series of ThO2 standards containing the analyte impurities in the range 10–100 (or 100–500) μg/g was prepared synthetically. The spectrometer
conditions were optimized to obtain calibration plots for the various analytes. The accuracy and precision of the developed
methodology for regular assay of ThO2 was evaluated by analyzing three synthetic samples. Further three secondary ThO2 standards were analyzed by EDRXF to check the developed methods. The determined concentrations of Ca, Cr, Fe, Ni and Cu were
in good agreement with the certified values of the secondary standards. 相似文献
809.
K x‐ray satellites, hypersatellites and lines due to radiative Auger effect (RAE) of Ti, V, Cr, Mn and Fe were measured after exciting the samples with Ag bremsstrahlung at 35 kV. All the lines were measured with the ‘Spectroscan VY’ spectrometer of Spectron—OPTEL, Russia, in which a curved LiF(200) crystal was used. The spectra were deconvoluted using Voigt functions, and the peak positions of the satellites and hypersatellites were determined with errors of ± (1–5) eV. The energy shifts of the satellite lines with respect to their parent lines were also obtained. Multi‐configuration Dirac–Fock (MCDF) calculations with the inclusion of higher‐order corrections were carried out to predict the peak positions of the satellite and hypersatellite lines. Our data were then compared with our own calculated values and also with the data of others. Our measured energy shifts for KαL1, KαL2, Kαh and KβL1, when compared with our MCDF calculations, show a maximum deviation of 8, 12, 2 and 20% respectively. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
810.
Mangesh Bhattarai Vineet Bharti Vasant Natarajan Armen Sargsyan David Sarkisyan 《Physics letters. A》2019,383(1):91-96
We study the sign of resonances obtained in electromagnetically induced transparency (EIT). Resonances of both kinds—bright (corresponding to enhanced absorption) and dark (corresponding to reduced absorption)—are obtained when the frequency of a probe beam is scanned. The experimental results, presented earlier, use magnetic sublevels of a hyperfine transition in the D1 line of 87Rb along with a magnetic field of 27 G. The atoms are contained in a vapor cell at room temperature, and with anti-relaxation coating on the walls. A quantitative theoretical model, which reproduces the experimental results quite well, is presented for the first time. The model solves the density matrix of the sublevels involved, and uses two regions—one with both the light and magnetic field, and the second without light and just a magnetic field. This ability to have both bright and dark resonances promises applications in sub- and super-luminal propagation of light. 相似文献