Extraction of vanadium(V) from acid solutions with octyl alcohol isomers

Vanadium(V) extraction with octyl alcohol isomers from acid solutions was studied. Two areas are determined, wherein the vanadium(V) extraction in relation to acidity of the aqueous phase is maximal. The opposite effects of temperature on the extraction are found. The mechanism of the vanadium(V) extraction with high molecular weight alcohols from weakly acid solutions was suggested.     

Syntheses and structures of the cobalt, nickel, and zinc complexes with 1,4-diaza-1,3-butadiene ligands

Several cobalt(II), nickel(II), and zinc(II) complexes with a series of ligands of the 1,4-diaza-1,3-butadiene type bearing aryl (2,6-di-iso-propylphenyl, mesityl) and alkyl (tert-butyl, iso-propyl) substituents at the nitrogen atoms are synthesized. The obtained complexes are characterized by X-ray structure analysis, IR spectroscopy, and elemental analysis.     

Synthesis of Heterocycles Based on α,β-Unsaturated P(III) Derivatives

Abstract

A general method of phosphorus heterocycle synthesis has been developed. It is based on the interaction between α,β-ethylene, acetylene P(III) derivatives and reagents, which contain electrophilic and nucleophilic centres in α,β- and α,β-positions, e.g. compounds with activated multiple bonds; β-halogenalcanols and thiols; nitrilimines, nitrilylides as 1,3-dipoles. This process is an unsynchron-ic ionic cycloaddition which begins with the attack of a phosphorus atom to the electrophilic centre of a reagent.     

Photoinduced Halophosphination of Unsaturated Compounds

Abstract

Comprehensive studies of photoinduced addition of phosphorus trihalides to unsaturated compounds, i.e. alkenes, alkynes, alkadienes, and enynes, were carried out. The addition of phosphorus trihalides to unsaturated C?C bonds is proved to be a radical chain process, the total reaction irate increasing with the increase of electron density on the unsaturated C?C bond. The photoinduced reaction of alkenes with PRr3 goes via Br atom attack on the least substituted C-atom of an unsaturated C?C bond and mainly results in the formation or dibromophosphines with a phosphorus atom in the second position of the carbon chain ?(1–2)-addition. In the case of polysubstituted alkenes an alternative direction of the reaction is realized, namely the photoinduced substitutional dibromophosphination to alkyl group. The reaction with alkynes results only in the formation of the products of (1–2)-addition. The Regioselectivity of the addition of phosphorous trihalide fragments to the substrate containing a heteroatom at the unsaturated C?C bond is determined by the stability of the secondary halogenoalkenyl(alky1) radical.     

Complexes of Lanthanide Nitrates with Alkyl Esters of Bromomethylenediphosphonic Acid

Complexes of lanthanide nitrates (La, Ce, Sm, Gd, Er, and Yb) with tetraethyl and tetraisopropyl esters of bromomethylenediphosphonic acid were prepared. The complexes were characterized by elemental analysis, IR spectroscopy, and, in some cases, NMR. The data confirm that diphosphonates coordinate with two P[dbnd]O groups, and there are no indications for the existence of noncoordinated P[dbnd]O groups. The structure of the complexes depends only on the ionic radius of the central metal atom and not on changes in the electronic or steric behavior of the ester groups. For the complexes of La, Ce, Sm, and Gd nitrates, the formula is LnL₂(NO₃)₃, and for Er and Yb nitrates it is Ln₂L₃(NO₃)₆ (Ln[dbnd]La, Ce, Sm, Gd, Er, Yb; L = diphosphonate).     

Studying the volatility of pyrazolone complexes of rare-earth elements by means of Knudsen effusion

The temperature dependences of the pressure of saturated vapor of pyrazolone complexes of rare-earth elements Ln(PMIP)₃ (where Ln = Y, Ho, Er, Tm, Lu; PMIP = 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone) are studied via Knudsen effusion, and the enthalpy of their sublimation is determined. Mass spectra and differential scanning calorimetry data are obtained.     

Spin correlation in Pr IV and Tm IV free ions

The coefficients \(c_{k}\) (k = 2, 4, 6) that pertain to spin-correlated matrix elements of the tensor operator \({{\varvec{U}}}^{{\varvec{(k)}}}\) have been evaluated by means of the differences \({{\varvec{U}}}^{{\varvec{(k)}}}\) (intermediate) \(-\) \({{\varvec{U}}}^{{\varvec{(k)}}}\) (LS) and the reduced matrix elements of the operator \({{\varvec{V}}}^{{\varvec{(1k)}}}\) . Only spin-allowed transitions have been considered from each ground level to the excited energy levels within the \(4\hbox {f}^{2}\) and \(4\hbox {f}^{12}\) configurations of the free ions Pr (3+) and Tm (3+), respectively. The values of the coefficients \(c_{k}\) thus found correspond in most cases by sign and order of magnitude to those determined in other sources as corrections to lanthanide (3+) crystal-field parameters.     

Preparing surfaces for the analysis of magnetic structures

The effect of plasma cleansing on the surface state of samples studied by electron microscopy is experimentally investigated. This technique of sample preparation allowed diagnostics of the magnetic states of objects by scanning electron microscopy with the analysis of spin polarization of secondary electrons.     

Dusty plasma structures in He-Kr DC glow discharge

Ion drift in gas mixtures has certain properties that can be used to generate ion flows with desired characteristics. For example, when the field is strong, ion heating is significant, and there is a large difference in atomic weight between ions and atoms, the ion velocity distribution can be highly anisotropic. Ion distribution anisotropy, in turn, can cause a substantial change in properties of dust structures in plasmas. Experiments on dusty plasma structures in glow discharge in mixtures of light and heavy gases (helium and krypton) are performed, and results of numerical simulations of ion and electron drift in the mixture are presented.     

Production of mirror nuclei <Superscript>7</Superscript>Li and <Superscript>7</Superscript>Be in <Superscript>16</Superscript>O<Emphasis Type="Italic">p</Emphasis> interactions at a momentum of 3.25 GeV/<Emphasis Type="Italic">c</Emphasis> per nucleon

Results of a comparative analysis of processes leading to the production of mirror nuclei ⁷Li and ⁷Be in ¹⁶Op collisions at a momentum of 3.25 GeV/c per nucleon are presented. A comparison of associated multiplicities of accompanying particles is performed. The first results on the mean multiplicity of neutrons appearing as fragments are described.