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Vol 63, No 5 (2018)
- Year: 2018
- Articles: 20
- URL: https://journal-vniispk.ru/0036-0236/issue/view/10290
Synthesis and Properties of Inorganic Compounds
Synthesis of NH4TiOF3 Crystals in the Presence of Polyoxyethylene Ethers
Abstract
The effect of polyoxyethylene ethers as surfactants on the morphology of NH4TiOF3 crystals obtained by hydrolysis of (NH4)2TiF6 in the presence of boric acid is analyzed. Depending on the molecular weight of the polyoxyethylene ether, the geometric dimensions (thickness and lateral size) of the crystals change. The obtained samples were characterized by X-ray and electron diffraction, Raman spectroscopy, and scanning electron microscopy. The heat treatment of NH4TiOF3 powders gives anatase mesocrystals retaining the initial particle morphology.
567-573
Polymer Technology of Porous SiC Ceramics Using Milled SiO2 Fibers
Abstract
The paper describes a developed polymer composition and a process for manufacturing highporous chemically pure silicon carbide ceramics from this composition, using milled industrial wastes of quartz fiber non-woven fabrics as the source of silicon dioxide, which is important as a rational utilization of these wastes. The necessity of pre-milling of the SiO2 fibers was experimentally substantiated. Without this stage, the duration of treatment at 1400°C under dynamic vacuum considerably (≥12 h) increased, because of the non-uniform distribution of the components in the polymer composite. In the case of stoichiometric ratio of SiO2 and carbon formed upon pyrolysis of the polymeric phenol binder, the obtained SiC ceramic contained a large amount of unreacted carbon. This indicaties that side reactions take place to give volatile silicon monoxide, which is distilled off from the reactor. The effects of the milling time of SiO2 fibers and the carbothermal reduction temperature on the elemental and phase composition, density, and porosity of the obtained samples and the ultimate compressive strength were studied. Analysis of the experimental results served for optimization of the composition of the initial polymer composites. As a result, highly porous (83%) and relatively strong (ultimate compressive strength of 8.2MPa) SiC-ceramic samples free from unreacted carbon and silicon dioxide and other stubborn impurities were fabricated at 1400°C (dynamic vacuum, heat treatment for 4 h).
574-582
Behavior of Impurities of Polpino Phosphorites in Acid Extraction
Abstract
The phase composition of phosphorites from the Polpino deposit (Bryansk oblast, Russia) is studied. The phosphorites are shown to be highly likely to contain α-quartz, phosphate substance, and clay mineral phases, in addition to the two major phases. The textural characteristics of Polpino phosphorites are determined as dependent on the temperature of preliminary heat treatment. The behavior of impurities upon hydrochloric acid decomposition of Polpino phosphorites is investigated. Iron and aluminum impurities are found to not interfere with the acid extraction of the phosphate substance.
583-586
Pore Structure and Properties of Silica Gels Prepared in Emulsions
Abstract
Silica gels having a developed mesopore structure with mean pore diameters in the range 10–20 nm have been prepared by sol–gel emulsion technology. A correlation has been found between the synthesis parameters, pore structure characteristics, adsorption properties, and stability of the material prepared.
587-590
Coordination Compounds
Chemical Processes in Systems CuI(CuII)/L/[B12H12]2–/solv (L = bipy, phen; solv = CH3CN, DMF, and CH2I2)
Abstract
Processes proceeding in the CuI(CuII)/L/(L = bipy, phen) systems in the presence of the [B12H12]2– anion, which has the lowest reduction ability among the boron cluster anions [BnHn]2– (n = 6, 10, 12), have been studied. It has been found that the preparation of CuI and heterovalent CuI/CuII complexes with azaheterocyclic ligands and the [B12H12]2–anion requires the CuII reduction process to be initiated. To minimize the redox process in the CuI/L/[B12H12]2– system, redox-active starting components have been added to the reaction system. Mono- and polynuclear copper complexes with various composition and structures have been isolated as a result of redox reactions proceeding in the CuI(CuII)/L/[B12H12]2–/solv (L = bipy, phen; solv = CH3CN, DMF, CH2I2) systems.
591-596
Crystal Structure of (H3O)2[(UO2)2(SO4)3(H2O)] · 6.86H2O, a New Hydroxonium Diuranyltrisulfate Aqua Complex
Abstract
Single crystals of earlier unknown hydroxonium monoaquatrisulfatodiuranylate 6.86-hydrate (H3O)2[(UO2)2(SO4)3(H2O)] · 6.86H2O (I) have been synthesized via the evaporation of an aqueous [UO2(NO3)2(H2O)2] · nH2O (n = 2, 4) solution containing sulfuric and nitric acids in air at room temperature. The structure of complex I has been studied by X-ray diffraction. Crystals are monoclinic, а = 15.0903(12) Å, b = 9.9191(8) Å, c = 15.6099(13) Å, β = 112.560(1)°, space group P21/n, Z = 4, V = 2157.7(3) Å3. The complex is formed due to electrostatic attraction forces between counterions and stabilized by hydrogen bonds. Its main structural element is the [(UO2)2(SO4)3H2O] n2- framework. The structure contains two types of uranium atoms surrounded by oxygen atoms according to a pentagonal bipyramid motif. The coordination polyhedra of all the three crystallographically different S atoms are SO42- tetrahedra. The U(1) atom in the equatorial bipyramid plane is monodentately bonded to the oxygen atoms of five SO42- tetrahedra, while the U(2) atom is monodentately coordinated to four sulfate groups and one water molecule.
597-603
604-609
Effects of the Nature of Transition Metal on the Composition and Structure of Reaction Products of M[(OOCC5H4)Mn(CO)3]2[O(H)Me]4 (М = Cu(II), Ni(II), Co(II), or Mn(II)) with 1,10-Phenanthroline
Abstract
Reactions of M[(OOCC5H4)Mn(CO)3]2[O(H)Me]4 (M = Ni(II), Co(II), or Mn(II)) adducts with 1,10-phenanthroline in chloroform at room temperature are found to yield complexes PhennM[(OOCC5H4) Mn(CO)3]2 (Co(II) or Mn(II), n = 2; M = Ni(II), n = 3). A similar reaction of dimeric Cu2[μ-(OOCC5H4) Mn(CO)3]4[O(H)Me]2 yields mononuclear PhenCu[(OOCC5H4)Mn(CO)3][O(H)Me] · MeOH. The resulting complexes are isolated in high yields and characterized by chemical analysis, IR spectroscopy, and X-ray crystallography.
610-617
Coordination Polymers Formed by the Reactions between Zn(II), Co(II), and Ni(II) Cimantrenates and γ,γ'-Dipyridyl in Methanol
Abstract
Reactions between methanol adducts of Zn(II), Co(II), and Ni(II) cimantrenates and γ,γ′-dipyridyl in methanol have been found to result in the formation of 1D coordination polymers, whose structure is governed, according to X-ray diffraction data, by the nature of the transition metal.
618-625
Hexa(isothiocyanato)chromates(III) of Some Yttrium Group Lanthanide(III) and Europium Complexes with Nicotinic Acid: Synthesis and Crystal Structures
Abstract
Double ionic complexes [M(C5H5NCOO)3(H2O)2][Cr(NCS)6] · nH2O, where M = Eu (I), n = 1.15; Dy (II), Er (III), n = 1.5; M = Yb (IV), n = 2, have been synthesized by the reaction between M(NO3)3, M = Eu, Dy, Er, Yb, K3[Cr(NCS)6], and nicotinic acid (C5H5NCOO) in an aqueous solution and studied by chemical analysis, IR spectroscopy, and X-ray diffraction. Crystals of complexes I–IV are monoclinic, space group P21/n, Z = 4; a = 9.5358(2) Å, b = 25.4871(5) Å, c = 15.4303(4) Å, β = 105.513(1)°, V = 3613.6(1) Å3, ρcalcd = 1.799 g/cm3 for I, a = 9.5901(5) Å, b = 25.8599(15) Å, c = 15.6316(9) Å, β = 106.829(2)°, V = 3710.6(4) Å3, ρcalcd = 1.782 g/cm3 for II, a = 9.5640(3) Å, b = 25.8936(11) Å, c = 15.6498(7) Å, β = 106.895(2)°, V = 3708.3(3) Å3, ρcalcd = 1.791 g/cm3 for III, and a = 9.5049(2) Å, b = 25.6378(4) Å, c = 15.5120(3) Å, β = 106.934(1)°, V = 3616.1(1) Å3, ρcalcd = 1.864 g/cm3 for IV.
626-630
Structural Features of Monomeric Octahedral d2-Rhenium(V) Monooxo Complexes with Oxygen Atoms of О, N Bidentate Chelating Ligands (Ln). Part 1: [ReO(Ln)(Lmono)3] Complexes Containing Five-Membered Chelate Rings ReNC2O
Abstract
Structural features of 31 mononuclear octahedral d2-Re(V) monooxo complexes with singly charged oxygen atoms of bidentate chelating (О, N) ligands (Ln) [ReO(Ln)(Lmono)3] (n = 1–19; Lmono is a monodentate ligand) have been considered. The O(Ln) atoms are trans to the О(oxo) ligands.
631-641
Physical Methods of Investigation
Tin Domain Growth on Quasi-Two-Dimensional CdTe and CdSe Nanoparticles
Abstract
Tin domain growth on quasi-two-dimensional colloidal CdSe and CdTe nanoparticles having the zinc blende structure has been studied. The initial quasi-two-dimensional CdSe and CdTe nanoparticles having lateral sizes of 100–200 nm were prepared by a colloidal method. Tin domain growth was accomplished in tetrahydrofuran via the reduction of a tin(II) salt by tetrabutylammonium borohydride. The tin domains had sizes of 10–20 nm as probed by TEM. In case of CdSe nanoparticles, tin domains were grown inside the inner cavities of initially rolled nanoparticles. A β-tin phase was identified by X-ray diffraction. The absorption spectra featured the broadening of exciton bands corresponding to quasi-two-dimensional nanoparticles, the spectral positions of absorption peaks remaining almost unchanged.
642-646
Relationship between the Structure and Nonlinear Optical Properties of R[UO2L3] and R3[UO2L3]4 Crystals (L—Carboxylate Ion)
Abstract
The nonlinear optical activity (Q) of uranyl carboxylates containing [UO2(L)3]– complexes in the crystal structure, where L is the anion of aliphatic or unsaturated monocarboxylic acids, has been characterized for the first time by the second harmonic generation method. It has been shown using molecular Voronoi–Dirichlet polyhedra that specific features of the cationic sublattice of U and R atoms in carboxylate structures depend on noncovalent interactions between outer-sphere R+ cations and [UO2(L)3]– complex anions. The existence of a relationship between Q and the magnitude of the vector characterizing the displacement of the uranium atom nucleus from the centroid of its Voronoi–Dirichlet polyhedron in the cation sublattice of U and R atoms is revealed.
647-654
Onium Sulfates and Hydrogen Sulfates: Products of Reactions of Sulfur(IV) Oxide with Aqueous Solutions of Alkylamines and Aniline
Abstract
The reaction products formed in the SO2–L–H2O–O2 systems (L is n-propylamine, n-butylamine, tert-butylamine, n-heptylamine, n-octylamine, aniline) were isolated and identified as “onium” salts [n-C3H7NH3]2SO4, [n-C4H9NH3]2SO4, [t-C4H9NH3]2SO4, [n-C7H15NH3]3SO4(HSO4), [n-C8H17NH3]3SO4(HSO4), and [C6H5NH3]2SO4. The products were characterized by elemental analysis, IR and Raman spectroscopy, mass spectrometry, and thermogravimetry.
655-660
Synthesis and Luminescent Properties of Terbium(III) and Europium(III) Fluoride Nanoparticles Modified with Aromatic Carboxylic Acids
Abstract
Europium(III) and terbium(III) fluoride nanoparticles modified with citric, anthranilic, benzoic, salicylic, and acetylsalicylic acids have been obtained by means of sorption from solution and modification in statu nascendi. The shape and size of the particles have been determined by scanning electron microscopy. The luminescence of the samples was studied and it has been established that terbium fluoride nanoparticles modified with acetylsalicylic acid exhibits the highest luminescence intensity.
661-664
Comparative Structural Characteristic of Aqueous Lanthanide Chloride Solutions at 1 : 40 Molar Ratio from X-ray Diffraction Data
Abstract
Aqueous lanthanide chloride solutions with 1 : 40 molar ratio have been studied by X-ray diffraction. Quantitative characteristics of the short-range environment of ions in solutions have been determined using model approach to analysis of experimental data. It has been confirmed that the number of molecules in the short-range environment decreases from nine to eight on passing from light to heavy cations. In so doing, three-caped trigonal prism coordination spheres of cations become two-caped one. Cations also form second coordination spheres composed of 8–10 solvent molecules. Noncontact ion associates form in all the systems.
665-669
Physicochemical Analysis of Inorganic Systems
System RbF–RbBr–Rb2SO4
Abstract
The three-component system RbF–RbBr–Rb2SO4 has been studied by differential thermal analysis (DTA). The melting temperatures and compositions corresponding to a eutectic point and a peritectic point have been determined. Invariant, monovariant, and divariant equilibrium states are described.
670-674
Phase Equilibria of Three-Component Reciprocal System Na,K║I,MoO4
Abstract
The three-component reciprocal system Na,K║I,MoO4 has been studied by differential thermal analysis (DTA). The compositions and melting temperatures have been determined, and the enthalpies of melting of eutectic mixtures measured. Phase equilibria in the system are described, and phase fields are demarcated.
675-681
Physical Chemistry of Solutions
Synthesis and Spectral Properties of Ni(II), Pd(II), Pt(II), and Pt(IV) Tetraphenyltetrabenzoporphyrinates
Abstract
Complexation reactions of 5,10,15,20-tetraphenyltetrabenzoporphyrin and transmetallation of its cadmium complex with nickel(II) acetate, Ni(II), Pd(II), and Pt(II) chlorides in dimethylformamide and phenol have been studied. The corresponding Ni(II), Pd(II), and Pt(II) porphyrinates have been synthesized. PtIVBr2 porphyrinate has been obtained by the treatment of Pt(II) 5,10,15,20-tetraphenyltetrabenzoporphyrinate with bromine in chloroform. The obtained compounds have been characterized by elemental analysis, electronic absorption and 1H NMR spectroscopy and mass spectrometry.
682-686
Effect of the Composition of Ethanol–DMSO Solvents on the Stability of Silver(I) Complexes with 18-Crown-6
Abstract
The effect of composition of ethanol–dimethyl sulfoxide (EtOH–DMSO) solvents (χDMSO = 0.0–1.0 mole fractions) on the stability of silver(I) complexes with 18-crown-6 ether (18C6) has been studied potentiometrically at 298.15 K. The increasing of DMSO concentrations in mixed solvents are shown to considerably reduce the stability of 18C6 complexes with silver(I) ion ([Ag18C6]+). A change in the solvation state of the central ion is suggested to be the key factor in shifting complexing equilibrium.
687-690