Synthesis and characterization of square-planar palladium(II) complexes containing anti- and syn-furan-2-aldoxime

Summary Fifteen palladium(II) square-planar complexes containing monodentate and/or bidentate anti- and syn-furan-2-aldoxime (FDH) have been isolated and characterized by elemental analysis, molecular weight determination, conductance studies, magnetic moments and i.r. spectral studies. The monodentate ligand coordinates through the nitrogen atom while the bidentate ligand coordinates through the furan oxygen atom and the nitrogen atom. The C-O-C stretching frequency of the furan ring may be taken as the criterion for the denticity of this ligand and is observed at 1240 and 1270 cm^– in anti- and syn-furan-2-aldoxime respectively. A shift to lower frequency occurs (in the complex) if the ligand is bidentate, however this frequency is unaffected if the ligand is monodentate.     

Cumulative yields of short-lived isotopes of barium in the spontaneous fission of252Cf

Cumulative yields of short-lived/barium isotopes^{139, 141, 142}Ba have been determined in the spontaneous fission of²⁵²Cf, using fast radiochemical separation and gamma-ray spectrometry.¹⁴²Ba yield is reported for the first time. The measured cumulative yields are converted to chain yields, assuming normal charge distribution systematics for comparision with the literature data.     

Cumulative yields of the short-lived ruthenium isotopes in the spontaneous fission of252Cf

⁶⁷Ga is produced by the⁶⁶Zn(d,n) reaction at 9 MeV bombarding energy. Deuterons of about 30 A obtained from the T-11 Tandem accelerator are used to bombard targets of natural Zinc prepared by electroplating onto thick copper disks. Radiochemical separation of gallium is performed by using a cation exchange column. The optimum conditions for an efficient separation are given in detail.     

Spectral studies, cyclic voltammetry and synthesis of cobalt(II) and ruthenium(III) complexes with symmetric and asymmetric ring containing membered N2S2, N4, and N5 donor macrocyclic ligands

Reaction of divalent cobalt(II) and trivalent ruthenium(III) salts (NO3, SCN and SO4) with macrocyclic ligands L1, L2 and L3 having N2S2, N4 and N5 core, have been designed and carry out. All these three macrocyclic ligands and their complexes were obtained in pure form. Their structures were investigated by using microanalytical analyses, IR, mass, magnetic moments, electronic and EPR spectral studies. The redox properties of the complexes were also examined by cyclic voltammetry. An interesting feature of complexes is that the relatively large rings of macrocyclic ligands prevent the macrocyclic rings from approaching the metal center as closely as they would, if they were not constrained. So the Ru-N distances are longer than expected due to ring size. Electrochemical studies show that the macrocyclic ligand L1 is more effective electron donors to ruthenium than of L2 and L3. Electronic spectral properties also show that the sulphur donor atom of L1 weakens the ligand field with respect to ligand-to-metal charge-transfer band. However it is expected that second-row transition metal-ligand bonds tend to be weaker than third-row transition metal-ligand bonds. There are well-established examples of reactions in which decreased of reactivity down a triad of transition metals is not observed. These novelties are usually attributed to pi-bonding effects for ligands such as carbon monoxide, solvent effects, or a change in mechanism.     

Determination of UV-transparent compounds by liquid chromatography using the UV detector

An indirect UV photometric detection technique is described in which a low concentration of a UV-absorbing compound (UVAC) is added to the mobile phase in reversed phase liquid chromatography, thereby making it possible for non UV-absorbing compounds such as the lower alcohols to be detected by the UV detector. This happens because the injected analyte may extract a portion of the UV absorbing compound from the mobile and/or stationary phase and the complex is co-eluted as a positive peak at the retention time of the analyte. Alternatively, the injected analyte may appear as a negative peak if the UV-absorbing compound is transferred to the mobile and stationary phases. In any case, the injected compound appears either as a positive or negative peak depending on the relative polarities and concentrations of all the compounds in the system. In addition, the resulting excess or deficiency of detection agent in the stationary phase is eluted separately as a positive or negative peak, indicating that the system has returned to equilibrium. In the work described herein, the chromatographic conditions and variables of the indirect photometric technique were studied to develop a quantitative HPLC method for UV-transparent compounds. It was found that under optimal conditions it is possible to determine some analytes quantitatively at concentrations as low as 0.05%.     

Spectrophotometric determination of isoproturon using p-aminoacetophenone and its application in environmental and biological samples

A simple and sensitive method for the determination of isoproturon, a widely used herbicide is described here which is based on alkaline hydrolysis of isoproturon to its corresponding primary amine followed by diazotization and coupling with p-aminoacetophenone in alkaline medium. The absorption maxima of the coloured compound formed is measured at 525 nm. Beer's law is obeyed over the concentration range of 0.5-5.0 mug in a final solution volume of 25 ml (0.02-0.2 ppm). The molar absorptivity and Sandell's sensitivity were found to be 8.6x10(5) l mol(-1) cm(-1) and 0.0002 mug cm(-2), respectively. The method has been satisfactorily applied to the determination of isoproturon in environmental and biological samples.     

Localized vibrations of H−Na+H− impurity in KCl crystal

Localized modes due to H^?Na⁺H^? complex impurity in KCl crystal have been computed by a Green function method and compared with experimental data.     

Quantitative estimations of ferric iron by phosphoric acid in aqueous-alcoholic medium

Summary The only method recommended for the direct estimation of ferric iron in presence of HCl is to reduce the ferric iron to ferrous iron and then to titrate against KMnO₄ solution by adding Reinhardt-Zimmermann reagent (MnSO₄ + H₂SO₄ + H₃PO₄). The solubility of the phosphato complexes of ferric chloride and phosphoric acid is much reduced by adding a nonaqueous solvent, ethyl alcohol or acetone. This property has been availed of to find out a method of estimating ferric iron directly against standard solution of phosphoric acid in aqueous-nonaqueous medium using K₄Fe(CN)₆ or cupferron as external indicators. A slight discrepancy at the end point, however, exists in the direct titration but it can be removed by applying a correction factor determined from the estimated results.     

Comparison of compositional and morphological atom-probe tomography analyses for a multicomponent Fe-Cu steel.

A multicomponent Fe-Cu based steel is studied using atom-probe tomography. The precipitates are identified using two different methodologies and subsequent morphological and compositional results are compared. The precipitates are first identified using a maximum separation distance algorithm, the envelope method, and then by a concentration threshold method, an isoconcentration surface. We discuss in detail the proper selection of the parameters needed to delineate precipitates utilizing both methods. The results of the two methods exhibit a difference of 44 identified precipitates, which can be attributed to differences in the basis of both methods and the sensitivity of our results to user-prescribed parameters. The morphology of the precipitates, characterized by four different precipitate radii and precipitate size distribution functions (PSDs), are compared and evaluated. A variation of less than approximately 8% is found between the different radii. Two types of concentration profiles are compared, giving qualitatively similar results. Both profiles show Cu-rich precipitates containing Fe with elevated concentrations of Ni, Al, and Mn near the heterophase interfaces. There are, however, quantitative disagreements due to differences in the basic foundations of the two analysis methods.     

Zinc-catalyzed Williamson ether synthesis in the absence of base

Zinc powder was found to be a highly efficient catalyst for the synthesis of aromatic ethers using microwave heating in the presence of N,N-dimethylformamide as well as under stirring in an oil-bath using tetrahydrofuran as solvent without any inorganic base. This method can be used for selective mono-, di- or tri-O-alkylations.