Showing papers in "Russian Journal of Inorganic Chemistry in 2012"

Geometric parameters and energies of molecular structures of macrocyclic metal chelates in the ternary 3d M(II) ion-ethanedithioamide-ethanedial systems according to quantum-chemical DFT B3LYP calculations

Abstract: The thermodynamic and geometric parameters of isomeric macrotricyclic Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes with the (NSSN) coordination of the ligand donor centers formed in the reaction of corresponding hexacyanoferrates(II) with ethanedithioamide H2N-C(=S)-C(=S)-NH2 and ethanedial HC(=O)-CH(=O) in gelatin-immobilized matrix implants have been calculated by the hybrid B3LYP density functional theory method with the use of the 6–31G(d) basis set and the Gaussian 03 program package. The bond lengths and bond and torsion angles in these complexes have been reported, and it has been stated that the Mn(II), Co(II), and Cu(II) complexes are nearly planar, the Fe(II) and Ni(II) complexes are slightly nonplanar, while the Zn(II) complex exhibits a rather considerable deviation from coplanarity. The additional five-membered chelate ring resulting from template cross-linking is almost planar in all cases.

Stability of the Mo72Fe30 polyoxometalate buckyball in solution

Abstract: The stability of the [Mo72Fe30O252(CH3COO)12{Mo2O7(H2O)}2{H2Mo2O8(H2O)}(H2O)91] · ∼150H2O polyoxometalate (Mo72Fe30) with a buckyball framework structure in solution has been investigated as a function of the solute concentration, illuminance, the presence/absence of a polymer, and the acidity of the medium. The polyoxometalate ions can form association species with molecules of water-soluble nonionic polymers, such as polyvinyl alcohol and polyvinylpyrrolidone. Electrotransport properties of the polyoxometalate ions—mobility, transport number, and diffusion coefficient—have been measured. The catalytic activity and stability of Mo72Fe30 in a redox reaction have been evaluated.

Density functional theory calculation of molecular structures of (5656)macrotetracyclic 3d metal complexes with 4,12-Dithiooxo-1,8-dioxa-3,6,10,13-tetraazacyclotetradecanedione-5,11

Abstract: The geometric parameters of macrotetracyclic Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes with the (NNNN) coordination formed by the reaction of corresponding hexacyanoferrates(II) with thiocarbamoylmethanamide H2N-C(=S)-C(=O)-NH2 and formaldehyde in gelatin-immobilized matrices have been calculated by the hybrid B3LYP density functional theory method with the use of the 6-31G(d) basis set and the Gaussian 03 program package. The bond lengths and bond and torsion angles in these complexes have been reported. It has been stated that the additional six-membered chelate rings resulting from template cross-linking are nonplanar and are turned at rather large angles to the two five-membered rings (which are also noncoplanar). In the Fe(II), Co(II), and Ni(II) complexes, the O1 and O2 atoms and both six-membered rings are located on one side of the (NNNN) plane of the donor nitrogen atoms, whereas in the Mn(II), Cu(II), and Zn(II) complexes, they are located on both sides of this plane.

Synthesis and antioxidant activity of biocompatible maltodextrin-stabilized aqueous sols of nanocrystalline ceria

Abstract: A novel method is proposed for preparing biocompatible aqueous CeO2 sols, which allows purposefully adjusting particle sizes and biochemical properties of nanocrystalline ceria (NC). The usefulness of this method for preparing aqueous sols of Ce1 − x Gd x O2 − x/2 solid solutions is demonstrated. Nanocrystalline ceria has been demonstrated to have a size-dependent activity in hydroxyl radical inactivation and in protecting mouse fibroblast cells (L929) from oxidative stress induced by hydrogen peroxide administration.

Hydrolysis constants of tervalent lanthanum and lanthanide ions in 0.1 M KNO3 solution

Abstract: The hydrolysis constants K h of tervalent lanthanum and lanthanide ions at 25°C have been determined by pH titration against the background of 0.1 M KNO3. pK h values change monotonically from 8.53 for La(OH)2+ to 7.41 for Lu(OH)2+ and from 26.56 for La(OH)3 to 21.43 for Lu(OH)3.

Characteristic features of formation, synthesis, and properties of binuclear zinc(II) helicates with alkyl-substituted 3,3′-bis(dipyrrolylmethenes)

Abstract: On the basis of spectrophotometric studies, it was demonstrated that complexation of hydrobromides of seven alkylated 3,3′-bis(dipyrrolylmethenes) (H2L · 2HBr) with zinc(II) acetate dihydrate in DMF (298.15 K) includes successive steps of formation of binuclear helicates of two types: [Zn2(AcO)2L] (heteroleptic single-helix complex) and [Zn2L2] (homoleptic double-helix complex). An increase in the degree of alkylation of the pyrrole rings of the ligands from 4 to 10 methyl groups induces an increase of overall complexation constants from 7.60 to 13.73. The synthesis of helicates [Zn2L2] was described. The products were studied by elemental analysis and IR, 1H NMR, U/Vis, and fluorescence spectroscopy. The effect of the helicand structure and the solvent nature on the chromophore and fluorescence properties of [Zn2L2] was discussed. The kinetic stability of zinc(II) with decamethyl-substituted 3,3′-bis(dipyrrolylmethene) in HCl-DMF medium was estimated.

Synthesis of ultrafine yttrium aluminum garnet using sol-gel technology

Abstract: Mesoporous yttrium aluminum garnet Y3Al5O12 powders were prepared using sol-gel technology proceeding from solutions of metal alkoxoacetylacetonates. Xerogel microstructure was studied by SEM, and the fact of mesopores being formed was established. The temperature range within which Y3Al5O12 crystallizes in a dynamic mode from the xerogel was determined to be 850–950°C using an SDT Q600 TGA/DTA/DSC analyzer. A 1-h isothermal treatment of the xerogel was shown to reduce the garnet phase formation temperature to 800°C. At lower temperatures (400, 450 or 500°C), even long-term (6-h) calcination yielded X-ray amorphous powders with developed surfaces (specific surface areas were 230–350 m2/g). Powder particle coarsening was studied upon sintering for 2 and 4 h at 1000, 1200, and 1400°C.

Complexation of Ag+ ions with L-cysteine

Abstract: The complexation of Ag+ ions with L-cysteine anions (Cys2−) at 25°C was studied potentiometrically against the background of 0.1 M KNO3. The AgCys− (logβ = 11.14 ± 0.10), AgHCys (logβ = 20.77 ± 0.06), Ag2Cys (logβ = 20.32 ± 0.17), and Ag2HCys+ (logβ = 27.28 ± 0.12) soluble complexes were found to be formed.

Synthesis of Ultrafine Refractory Oxides Zirconia-Hafnia-Yttria by Sol-Gel Technology

Abstract: A transparent gel was prepared using a hydrolytically active solution of zirconium, hafnium, and yttrium alkoxoacetylacetonates. This gel served to synthesize ultrafine zirconia-hafnia-yttria complex oxide. The product dispersity was studied as affected by the parameters of xerogel heat treatment. The thermal behavior of the xerogel was studied by DSC-TGA. Elemental analysis (laser mass spectrometry) and phase analysis of the synthesized materials were carried out. Average crystallite sizes were calculated by the Scherrer relationship. The particle morphology was studied by TEM. Specific surface areas were determined. Sintering of ultrafine oxide powders was studied at 1000, 1200, and 1400°C.

Reaction of trans-[RuNO(NH3)4(OH)]Cl2 with nitric acid and synthesis of ammine(nitrato)nitrosoruthenium complexes

Abstract: The reaction of trans-[RuNO(NH3)4(OH)]Cl2 with nitric acid has been studied. Reaction products have been identified by IR spectroscopy, NMR, mass spectrometry, powder and single-crystal X-ray diffraction, and chemical analysis. Synthesis methods have been developed for amminenitrosoruthenium complexes containing outer-sphere and coordinated nitrate ions: trans-[RuNO(NH3)4(H2O)](NO3)3 (I), trans-[RuNO(NH3)4(NO3)](NO3)2 (II), and fac-[RuNO(NH3)2(NO3)3] (III). Complex II has two polymorphs: monoclinic and tetragonal. The latter has been studied by X-ray crystallography.

Colors of mixed-substituted double molybdate single crystals having scheelite structure

Abstract: X-ray diffraction, neutron diffraction, optical and absorption spectroscopy, electron probe microanalysis, and temperature-dependent electrical conductivity measurements were used to study structural features and defect generation to be responsible for coloring of single crystals of nominal compositions (Na05LaxGd05 − x)MoO4:Tm having scheelite structure which were Czochralski grown under a weakly oxidizing atmosphere followed by air annealing In nonannealed crystals, the color was found to be due to oxygen vacancies and their compensator electrons (black color) and, most likely, electrons located on Mo6+ ions (lilac color); the concentration of these defects decreased upon air annealing, thereby discoloring the samples The yellow color of crystals was interpreted as arising from possible formation of a color center (an association of a molybdenum vacancy and a hole)

Phase transition in mayenite Ca12Al14O33

Abstract: A phase transition in Ca12Al14O33 has been discovered and investigated by thermogravimetric analysis, differential scanning calorimetry, dilatometry, and high-temperature X-ray diffraction. The phase transition occurs at 922 ± 45 K (ΔH = −406 ± 13 kJ/mol, ΔS = −440 ± 14 J/(mol K)) and is presumably a first-order one. It does not change the symmetry of the cationic subsystem. The phase transition is difficult to reveal because the material changes its mass, probably by releasing water bound in several different ways.

Physicochemical Interaction in the System Si-Al-Ti-Ca-Mg- Fe-Na-K-O with the Consideration of the Formation of Solid Solutions

Abstract: Experimental investigation of the phase composi� tion of melts in the system Si–Al–Ti–Ca–Mg–Fe– Na–K–O is a difficult challenge because of high pro� cess temperatures, long time of equilibration, and simultaneous melt crystallization of three to four phases with significant overlap of their formation regions over a wide temperature range ( 1000– 1300°С).

Study of the stability of solid polyoxometalate Mo72Fe30 with a buckyball structure

Abstract: Samples of polyoxometalate Mo72Fe30: [Mo72Fe30O252(CH3COO)12{Mo2O7(H2O)}2 {H2Mo2O8(H2O)}(H2O)91] · ≈150H2O with a buckyball structure, which can be both crystalline and amorphous, were synthesized. It was shown that such samples can be studied by neutron diffraction. The stability of Mo72Fe30 to heating and UV light exposure (in poly(vinyl alcohol) and polyvinylpyrrolidone films) was studied by IR, EPR, and electronic absorption spectroscopy; thermal analysis; and mass spectrometry. Mo72Fe30 was found to be less stable to heating and irradiation in a poly(vinyl alcohol) film as compared with the related polyoxometallate Mo132 free of iron. The sorption properties of Mo72Fe30 to organic vapors and its stability under sorption conditions were studied. It was demonstrated that, in addition to sorption, organic substances cause the destruction of buckyballs.

Synthesis, structure, and luminescent properties of lanthanide coordination compounds with 3-methyl-4-formyl-1-phenylpyrazol-5-one

Abstract: An exchange reaction of the sodium salt of 3-methyl-1-phenyl-4-formylpyrazol-5-one (HL) with chlorides or nitrates of lanthanides (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, and Yb) was used to synthesize coordination compounds of composition LnL3·nSolv (Solv = H2O or EtOH). According to powder X-ray diffraction data, these compounds constitute two series: one comprises lanthanum and neodymium complexes, and the other, samarium, europium, gadolinium, terbium, dysprosium, and ytterbium complexes. For the complexes of the first series, the structure was solved in a single-crystal diffraction experiment carried out on [La2(μ-L)3(L)3(H2O)3]·2MeOH. The lanthanum atoms in the complex are at a distance of 4.222(2) — from each other, and they are structurally nonequivalent and linked by three 5-hydroxy-4-formylpyrazole anions. Solid-phase samples of the coordination compounds under study feature weak luminescence in the spectral regions intrinsic to lanthanide cations.

Extraction of palladium with thiacalix[4]arenes from nitric acid nitrate-nitrite solutions

Abstract: Calix[4]arene 1, thiacalix[4]arenes 2(LH4), and calix[4]arenethioether 3 were compared in palladium extraction from nitric acid solutions; DPd for 2 was shown to be 2–3 orders of magnitude larger than for 1 at pH > 3 (comparable with 3) because of cation-exchange and coordination extraction of palladium. It was shown by extraction methods and IR spectroscopy that thiacalixarenes 2 extract complex species [PdnLmH4 − 2n] (m = 1, n = 1 and 2) and [(PdA2)nLmH4] (A = m = 1, n = 1–4) from nitric acid solutions at pH 3. Extraction constants for these palladium species that satisfactorily describe experimental data were calculated. As distinct from 3, thiacalixarenes 2 are promising for the combined extraction of palladium and silver from alkaline solutions and the selective extraction of fission palladium from nitric acid solutions. Phosphorylated at the upper rim thiacalixarenes 2 can be considered as bifunctional extractants for the separation of fission radionuclides.

Composites based on cardo polybenzimidazole and hydrated silicon dioxide for phosphoric acid fuel cells

Abstract: Phosphoric acid-doped composites based on cardo polybenzimidazole and hydrated silicon dioxide have been synthesized. The effect of synthesis conditions on the properties of the resulting composites has been investigated. The silicon dioxide-modified membranes have a higher proton conductivity. Hydrated silicon dioxide substantially suppresses phosphoric acid washout from the hybrid membranes exposed to water vapor. The diffusion permeability of the composite membranes has been measured in solutions of various salts. Some membranes samples have been tested under fuel cell operation conditions.

Extraction of rare earth elements with 1-(diphenylphosphorylmethoxy)-2-diphenylphosphoryl-4-ethylbenzene with the use of 1,1,7-trihydrododecafluoroheptanol as a solvent

Abstract: Extraction of rare earth elements from nitric acid solutions in a 1,1,7-trihydrododecafluoroheptanol-water system with the use of phosphoryl-containing podand 1-(diphenylphosphorylmethoxy)-2-diphenylphosphoryl-4-ethylbenzene (L) was studied. The content of metals in organic phase was shown to be negligible at nitric acid concentration lower 1 mol/L. Distribution ratio sharply increases with nitric acid concentration from 1 mol/L and reaches 5.5 for the yttrium subgroup elements at HNO3 concentration of 6 mol/L. The rare earth elements of the yttrium subgroup were found to be extracted much better than the rare earth elements of the cerium subgroup under the same conditions, the distribution ratios in both subgroups smoothly rise with atomic number of element. It was shown using the shift of extraction equilibrium that the M: L ratio in extracted complexes is 1: 2 irrespective of the nature of rare earth element. The structure of complex {Yb[η2-(O,O′)-L]2(η2-O2NO)2}(O2NOHNO3), whose single crystals were isolated from extraction solution, was established by X-ray diffraction study. The system can be used for the isolation and separation of rare earth elements.

Synthesis and structure of tetra- and triphenylantimony salicylaldoximates

Abstract: Tetraphenylantimony salicylaldoximate (I) was synthesized by reactions of pentaphenylantimony with salicylaldoxime or triphenylantimony disalicylaldoximate in toluene. Triphenylantimony bis(salicylaldoximate) (II) was synthesized by the reaction between triphenylantimony, hydrogen peroxide, and salicyl- aldoxime. The structures of compounds I and II were determined by X-ray crystallography. The coordination of Sb atoms in I and II is a distorted trigonal bipyramid. For compounds I and II, Sb-C bond lengths are 2.1132(13)–2.1760(14) A and 2.1026(15)–2.112(2) A, the Sb-O distances are 2.1771(11) A and 2.0768(11) A, and the Sb…N intermolecular contacts are equal to 2.945(2) A and 2.882(2) A, respectively.

Microwave-hydrothermal synthesis of gadolinium-doped nanocrystalline ceria in the presence of hexamethylenetetramine

Abstract: A new method is proposed for producing nanodisperse ceriabased solid solutions, involving microwave-hydrothermal (MW-HT) treatment of aqueous solutions containing salts of cerium and dopant elements and hexamethylenetetramine (HMTA) The specifics of HMTA hydrolysis under hydrothermal conditions are studied Xray and electron diffract ion, Raman spectroscopy, and transmission electron microscopy are used to analyze the physicochemical characteristics of Ce1 - xGdxO2 - x/2 (x = 010, 015, 020) nanocrystalline solid solutions produced using the new method

DFT study of the structure and stability of Pu(III) and Pu(IV) chloro complexes

Abstract: The structural characteristics and energies of PuCl n (3 − n)+ and PuCl n (4 − n)+ complexes (n = 2–8) have been studied by the density functional theory (DFT) method in the SVWN5 local functional approximation.

Calculations of microconstants and equilibrium formation constants for platinum(II) and palladium(II) halide complexes in solution

Abstract: Distribution diagrams and formation functions for halide complexes [M(H2O)4 − n Cl n ]2 − n (M = Pt(II) or Pd(II)) and [PdCl4 − n Br n ]2− (n = 0–4) in solution are analyzed in terms of the matrix model. Equilibrium constants for binding the first ligand $$\left( {\bar K} \right)$$ and corrections for the mutual influence between ligands (ω) in the course of complex formation in solution are calculated. In examples analyzed, the substitution of chloride ion for water in the coordination sphere of platinum(II) and palladium(II) is an anti-cooperative process. The substitution of bromide ion for chloride ion in the coordination sphere of [PdCl4]2− is weakly cooperative. Quantum-chemical calculations show that platinum(II) and palladium(II) cis-bisaquadichloro complexes in the gas phase are thermodynamically less stable than trans-isomers. The cis-trans isomerization constants in the gas phase calculated by the DFT method and those found for solutions using the matrix model have the same order of magnitude.

Synthesis, crystal structure, and IR spectral study of Na[(UO2)(C3H7COO)3] · 0.25H2O and K[(UO2)(C3H7COO)3]

Abstract: Synthesis, IR spectral study and X-ray diffraction analysis of single crystals of Na[(UO2)(C3H7COO)3] · 0.25H2O (I) and K[(UO2)(C3H7COO)3] (II) were carried out. Compound I is monoclinic, unit cell parameters are: a = 13.5671(15) A, b = 20.070(2) A, c = 13.6139(15) A, β = 106.839(2)°, space group P21, Z = 8, R = 0.0493. Compound II is orthorhombic, unit cell parameters are: a = 17.1325(9) A, b = 19.6966(11) A, c = 21.9686(11) A, space group P212121, Z = 16, R = 0.0563. Mononuclear groups [UO2(C3H7COO)3]− related to the A 3 01 crystal-chemical group (A = UO 2 2+ , B 01 = C3H7COO−) of uranyl complexes are the uranium-containing structural units of crystals I and II. The data of IR spectral study agree well with X-ray diffraction data.

A new method of synthesis of the B 3 H 8 − anion

Abstract: A new method of synthesis of the B3H 8 − anion has been suggested. The method uses the reaction of some metal halides (CuCl, SnCl2, CrCl3, PbF2, PbCl2, PbBr2, and BiCl3) with sodium tetrahydroborate. It is characterized by high (up to quantitative) yields and simplicity of isolation of the target products ((n-C4H9)4N)[B3H8] and Cs[B3H8].

Interaction of rare-earth oxides with binary molten mixtures of zirconium and alkali metal fluorides

Abstract: Isothermal saturation, inductively coupled plasma mass spectrometry (ICP-MS), and X-ray powder diffraction were used to study solubilities of La2O3, Sm2O3, and Ho2O3 in the eutectic mixtures of LiF-ZrF4, NaF-ZrF4, and KF-ZrF4 systems at temperatures from 873 to 1073 K. The solubilities of rare earth oxides in the molten fluorozirconate systems studied decrease in the increasing order of Ln3+ ion radii and in the increasing order of alkali metal cation radii in the binary mixture. The thermodynamic parameters of dissolution calculated for the oxides imply the dominance of a chemical dissolution mechanism, and this implication was supported by X-ray powder diffraction data.

Siliciding of titanium carbides with gaseous SiO

Abstract: Titanium carbides of different stoichiometries were silicided with gaseous SiO at 1350°C. A mechanical mixture of silicon and silicon dioxide was used as a reaction source of SiO. Ti3SiC2, TiSi2, and Ti5Si3 were the main reaction products, the phase composition of which strongly depended on the titanium carbide stoichiometry. The siliciding of carbides with a nearly stoichiometric carbon content resulted in the formation of Ti3SiC2, on the surface of which the other silicide phases, such as Ti5Si3 and TiSi2, began to form. For titanium carbides with a low carbon concentration, Ti5Si3 was the only siliciding product.

Coordination of 5,10,15,20-tetraphenyl-21H,23H-porphin by rhenium in various oxidation states

Abstract: A method was developed for the synthesis of three rhenium complexes, (5,10,15,20-tetraphenyl-21H,23H-porphinato)(phenoxo)rhenium(III) (PhO)ReTPP, (5,10,15,20-tetraphenyl-21H,23H-porphi-nato)(chloro)rhenium(III) (Cl)ReTPP, and μ-oxo-bis[(oxo)-(5,10,15,20-tetraphenyl-21H,23H-porphi-nato)rhenium(V)] [O=ReTPP]2O, by one reaction between porphyrin H2TPP and H2ReCl6 in boiling phenol. In the complex formation reaction accompanied by the redox process, only the metal cation is involved in the transformation. Rhenium(IV) as chlororhenic acid dispropoportionates without participation of solvent or porphyrin to give Re(III) and Re(V) complexes. The chemical structures of the products were established by spectral and elemental analysis. Characteristics of the UV, Vis, IR, and 1H NMR spectra, the chromatographic mobility, and stability of the complexes were determined.

Synthesis and structure of quasi-one-dimensional zinc oxide doped with manganese

Abstract: Nanotubes of manganese-doped zinc oxide Zn1 − xMnxO (0 ≤ x ≤ 0.2) were synthesized by heating the Zn1 − xMnx(HCOO)(OCH2CH2O)1/2 precursor in air at 500°C. The precursor with extended crystals was synthesized by a solvothermal method based on heat treatment of a mixture of Zn1 − xMnx(HCOO)2 · 2H2O with an ethylene glycol excess at 100–130°C. The tubular morphology of Zn1 − xMnxO particles was identified by transmission electron microscopy. Tubular quasi-one-dimensional particles were shown to have a nanodispersed polycrystalline structure, the size of separate crystallites being from 5 to 20 nm. X-ray photoelectron spectroscopy suggested that the manganese distribution on the outer surface layer of Zn1 − xMnxO nanotubes is nonuniform.

Low-temperature sol-gel synthesis of modified nickel ferrite

Abstract: A low-temperature method has been developed for preparing nickel ferrite doped with cobalt and copper (Ni09Co01Cu01Fe19O4 − δ) This method provides the target product at 170–200°C with nanosized particles The role of ammonium nitrate in the considerable reduction of ferrite synthesis temperature was studied

Synthesis of TiO2-SiO2 xerogels via the hydrolysis of a tetrabutoxytitanium-tetraethoxysilane mixture in aqueous ammonia and hydrochloric acid atmospheres

Abstract: TiO2-SiO2 xerogels have been synthesized by the hydrolysis of tetrabutoxytitanium-tetraethoxysilane mixtures in a 10% aqueous ammonia vapor and concentrated hydrochloric acid vapor atmospheres under static conditions. The dependence of the physical and chemical properties of the xerogels on the synthetic conditions has been investigated.