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1.
Baranwal BP Gupta T 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(4):859-865
Some mixed-valence Fe(II) Fe(III) complexes of thiocarboxylic acids and straight chain fatty acids with general formula [Fe(II)Fe(III)(2)O(SOCR)(6)(H(2)O)(3)] and [Fe(II)Fe(III)(2)O(SOCR)(3)(OOCR')(3)(CH(3)OH)(3)] (where, R=CH(3) or C(6)H(5) and R'=C(13)H(27), C(15)H(31) or C(17)H(35)) were synthesized and characterized by elemental analyses, spectral (infrared, electronic and M?ssbauer) studies, molar conductance and magnetic susceptibility measurements. The infrared spectra suggested bridging nature of carboxylate and thiocarboxylate anions along with upsilon(asym)(Fe(3)O) vibrations in the complexes. M?ssbauer studies revealed two resolved quadrupole doublets at 120-315 K confirming the presence of Fe(II) and Fe(III) moieties in the complexes. This was supported by the observed electronic spectral bands in the complexes at room temperature. The spectrum showed a band at around 13,800 cm(-1) which indicated an intervalence-transfer. Magnetic susceptibility measurements showed weak antiferromagnetic coupling related to mixed-valence pairs with S(2)=2, em leader S(1)=S(3)=5/2 spin exchange model. Conductance data indicated, the complexes were non-electrolytes in nitrobenzene. A structure has been established on the basis of these studies. 相似文献
2.
The dissolution behavior of carbon steel in ammonium chloride (NH4Cl) solution containing sodium thiosulfate (Na2S2O3) of various concentrations (0.01 and 0.1 M) was investigated using electrochemical impedance spectroscopy (EIS) and other nonelectrochemical techniques. The weight loss and polarization measurements indicate a significant increase in the NH4Cl corrosion rate of carbon steel on addition of Na2S2O3. The EIS measurements exhibited two capacitive loops at multiple direct current (dc) potentials for both the concentrations. Electrical equivalent circuit (EEC) and reaction mechanism analysis (RMA) were employed to analyze the impedance data. A four-step mechanism with two intermediate adsorbate species of same charge was proposed to explain the dissolution behavior of carbon steel in the given system. The surface coverage values enumerated that the surface was entirely covered with adsorbed species unlike in the pure NH4Cl system. Charge transfer resistance and polarization resistance values estimated from RMA parameters indicate the increase in a dissolution rate with dc potential. The surface morphology was inspected via field emission scanning electron microscopy, and the corrosion products including surface state of carbon steel electrode were analyzed using energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. 相似文献
3.
Prince Kumar Baranwal R. Prasanna Venkatesh 《Journal of Solid State Electrochemistry》2017,21(5):1373-1384
The anodic dissolution of carbon steel in ammonium chloride (NH4Cl) solutions (5, 10, and 20 wt%) is investigated via various electrochemical techniques and other complementary techniques. The polarization measurements reveals that the carbon steel is susceptible to general corrosion. The impedance data taken at various overpotentials shows multiple loops, corresponding to capacitance, inductance, and negative capacitance, and the number of time constants observed is also not the same for various NH4Cl concentrations. From reaction mechanism analysis, a multi-step reaction mechanism with three adsorbed intermediates and three dissolution paths (one chemical path and two electrochemical paths) is proposed to describe the observed patterns in impedance measurements. The surface coverage of intermediate species and the contribution of chemical reaction and electrochemical reaction to the overall corrosion rate are also estimated from the proposed model. The results obtained from field emission scanning electron microscopy and Raman spectroscopy measurements are also reported. 相似文献
4.
Some mononuclear mixed-carboxylato ??-diketonato oxovanadium(IV) complexes of the general formula [VO(??-dike)(RCOO)] (where H??-dike?=?acetylacetone; benzoylacetone or dibenzoylmethane, R?=?C15H31 or C17H35) have been synthesized from VO(acac)2 by stepwise substitutions of acetylacetonate ion with straight chain fatty acids (RCOOH) and ??-diketones in p-xylene under reflux. The substituted acetylacetone could be fractionated out with p-xylene as an azeotrope. These were characterized by elemental analyses, molecular weight determinations, spectral (electronic, infrared, 1H NMR, EPR and powder XRD) studies, magnetic susceptibility measurements and cyclic voltammetry. Molar conductance values indicated the complexes to be non-electrolytes in nitrobenzene. Bidentate chelating nature of ??-diketonate and carboxylate ligands in the complexes was established by infrared and NMR spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. The EPR spectra illustrated coupling of the unpaired electron with 51V nucleus (I?=?7/2). Cyclic voltammograms of all the complexes displayed one-step oxidation processes. The oxidation peak potential corresponded to the quasireversible one-electron oxidation process of the metal center, yielding V(V) species. Powder XRD and transmission electron microscopy (TEM) studies indicated the particles of these were lying in the nano-size range. The synthesized complexes are a new type of mixed-ligand complexes in which vanadium is having coordination number 5. A square pyramidal geometry around vanadium has been assigned in all the complexes. 相似文献
5.
Vipul K. Baranwal Ram K. Pandey Manoj P. Tripathi Om P. Singh 《Communications in Nonlinear Science & Numerical Simulation》2012,17(10):3906-3921
A new analytic algorithm for highly nonlinear time fractional reaction–diffusion equations is proposed in this paper. The proposed method is an amalgamation of variational iteration method (VIM), Adomian decomposition method (ADM) and further refined by introducing a new correction functional. This new correction functional is obtained from the standard correction functional of VIM by introducing an auxiliary parameter γ and an auxiliary function H(x) in it. Further, a sequence Gn(x, t), with suitably chosen support, is also introduced in the new correction functional. The algorithm is easy to implement and only four to six iterations are sufficient for fairly accurate solutions. The algorithm is tested on Fitzhugh – Nagumo and generalized Fisher equations with nonlinearity ranging from 2 to 5. 相似文献
6.
A new dinuclear cobalt(II) complex containing monothioacetate and 3-methylsulfanylpropionate ligands was synthesized and fully
characterized by spectral, magnetic moment, electrochemical, elemental, thermal and FAB mass analyses data. In order to explore
the role of labile metal complexes in promoting phosphodiester hydrolysis, kinetic and mechanistic studies were performed.
The hydrolyses of ethyl 4-nitrophenylphosphate (ENPP) and the bis(4-nitrophenyl)phosphate (BNPP) complex are catalytic, as
determined by the observations of both rate enhancement and turnover. The pH versus rate profile indicates that deprotonation of the metal-coordinated water occurs to form the active catalyst. 相似文献
7.
Balram P. Baranwal Talat Fatma Rinkoo D. Gupta Tarkeshwar Gupta 《Transition Metal Chemistry》2007,32(4):501-506
Oxo-centered, trinuclear, mixed-ligand complexes of chromium(III) have been synthesized by stepwise substitutions of acetate
ions of [Cr3O(OOCMe)4(OOCR)3] · 3MeOH (1) and the isolated products of the type [Cr3O(OOCMe)2 (SB)(OOCR)3]PF6 · 3MeOH (2), [Cr3O(OOCMe)(SB)2(OOCR)3]PF6 · 3MeOH (3) and [Cr3O(SB)3(OOCR)3]PF6 · 3MeOH (4) [where R = C13H27 and HSB = C6H4(OH)CHNC6H4Cl] have been characterized by a full battery of complementary physico–chemical methods including spectral (infrared, electronic,
FAB mass and powder XRD) studies, elemental and thermogravimetric analyses, molar conductance and magnetic susceptibility
measurements. The infrared spectra suggest the bridging nature of both carboxylate and Schiff base anions along with ν
asym(Cr3O) vibrations in the complexes. The trinuclear nature of the complexes has been assessed from FAB mass data. Electronic spectra
and magnetic moment values were consistent with chromium(III) ion present in an octahedral environment which was supported
by their powder X-ray diffraction data. Cyclic voltammetric data of complex (4) indicate a reversible oxidation wave and an irreversible reduction wave in the range − 1.2–0.6 V. The decomposition pathway
of all the complexes has been discussed on the basis of thermogravimetric analysis data. Conductance data indicate the monocationic
nature of the complexes and their plausible structure has been established on the basis of above physico–chemical studies. 相似文献
8.
Balram P. Baranwal Talat Fatma Anand Varma Alok K. Singh 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(4):1177-1180
Some mixed-ligand thorium(IV) complexes with the general formula [Th(OOCCH3)4?nLn] (L = anions of myristic, palmitic or stearic acid and n = 1–4) have been synthesized by the stepwise substitution of acetate ions of thorium(IV) acetate with straight chain carboxylic acids in toluene under reflux. The complexes were characterized by elemental analyses, spectral (electronic, infrared, NMR and powder XRD) studies, electrical conductance and magnetic susceptibility measurements. Doubly and triply bridged coordination modes of the ligands were established by their infrared spectra and nano-size of the complexes by powder XRD. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes showed π → π*, n → π* and charge transfer transitions. Molar conductance values indicated the complex to be non-electrolytes. These are a new type of mixed-ligand thorium(IV) complexes for which a nano-sized, oxygen bridged polymeric structure has been established on the basis of physico-chemical studies. 相似文献
9.
Synthesis and physico-chemical studies of some polynuclear mixed carboxylate complexes of nickel(II)
B. P. Baranwal G. K. Parashar R. C. Mehrotra 《Monatshefte für Chemie / Chemical Monthly》1980,111(5):1203-1211
A number of polynuclear mixed carboxylates of nickel(II) with the general composition [Ni(OOCCH3)2–n
(OOCR)
n
]
x
(whereR=C13H27, C15H31, C17H35 and C21H43 andn=1 or 2) have been synthesized by the transacylation reactions of anhydrous nickel acetate with higher carboxylic acids in refluxing toluene. On recrystallization from benzene-alcohol mixtures, mono-alcoholate complexes, Ni(OOCCH3)2–n
(OOCR)
n
·ROH (whereR=CH3 and C2H5) have been isolated. All these derivatives have been characterized by the molecular weight determinations, infra-red and electronic reflectance spectra and magnetic susceptibility measurements.
Synthese und Eigenschaften einiger gemischter Carboxylat-Komplexe von Nickel(II)
Zusammenfassung Komplexe des Typs [Ni(OOCCH3)2–n (OOCR) n ] x (mitR=C13H27, C15H31, C17H35 und C21H43,n=1 oder 2) wurden aus wasserfreiem Nickelacetat mit höheren Carbonsäuren in siedendem Toluol erhalten. Bei der Kristallisation aus Benzol-Alkohol-Mischungen wurden Monoalkoholate Ni(OOCCH3)2–n (OOCR) n ·ROH (mitR=CH3 und C2H5) isoliert. Die Charakterisierung der Komplexe erfolgte mittels Molekulargewichtsbestimmung, Infrarot- und Elektronenspektren und der Messung der magnetischen Susceptibilität.相似文献
10.
G. Singh B. P. Baranwal I. P. S. Kapoor D. Kumar C. P. Singh R. Fröhlich 《Journal of Thermal Analysis and Calorimetry》2008,91(3):971-977
Three hexamethylenetetramine (HMTA) metal nitrate complexes such as [M(H2O)4(H2O-HMTA)2](NO3)·4H2O (where M=Co, Ni and Zn) have been prepared and characterized by X-ray crystallography. Their thermal decomposition have been studied
by using dynamic, isothermal thermogravimery (TG) and differential thermal analysis (DTA). Kinetics of thermal decomposition
was undertaken by applying model-fitting as well as isoconversional methods. The possible pathways of thermolysis have also
been proposed. Ignition delay measurements have been carried out to investigate the response of these complexes under condition
of rapid heating. 相似文献