Vol 64, No 4 (2019)

The detailed study of the solid solutions with the general composition La_{1 − x}Bi_xMn_{1 − y}Fe_yO_{3 + δ} (x = 0.1–0.3, y = 0.1–0.3) prepared by means of solid-phase synthesis has been performed for the first time. The synthesized samples crystallize in an R-centered trigonal unit cell at room temperature and have the oxygen nonstoichiometry index δ = 0.15. The existence of two types of crystallites with related but yet different space groups has been established for La_0.7Bi_0.3Mn_0.9Fe_0.1O_{3 + δ} by high-resolution transmission electron microscopy. All the samples experience chemical expansion at temperatures above 650°C. The thermal expansion coefficient is 11.6 × 10⁻⁶°C⁻¹ in the low-temperature region (25–650°C) and 12.3 × 10⁻⁶°C⁻¹ in the high-temperature region (650–1000°C). The electroconductivity of all the studied solid solutions in the temperature range 800–200°C is slightly lower than for undoped lanthanum manganite.

Ammonium aluminium carbonate hydroxide is synthesized by three different ways. The prepared samples and the products of their heat treatment (aluminium oxides) are studied by physicochemical methods. It is shown that the synthetic method used to prepare ammonium aluminium carbonate hydroxide has a significant effect on the structure, porosity, and dispersion of the resulting γ- and α-forms of aluminium oxide.

Two new lanthanide complexes [Ln(2,3-DClBA)₃(CH₃CH₂O)(H₂O)]_2n · n(4,4′-bipy) (Ln = Eu (1),Tb (2); 2,3-DClBA = 2,3-dichlorobenzate; 4,4′-bipy = 4,4′-bipyridine) have been synthesized by aqueous solution synthesis and characterized by elemental analysis and X-ray crystallography analysis. The results showed that complexes 1 and 2 are isostructural and are built of two-dimensional layered structures. Complex 1 belongs to triclinic system, space group P1̄, a = 9.7239(7) Å, b = 12.0736(13) Å, c = 14.6611(12) Å, α = 103.356(2)°, β = 93.0140(10)°, γ = 97.6200(10)°, V = 1653.7(3) ų, Z =1, ρ = 1.735 g/cm³, μ = 18.453 mm⁻¹, F(000) = 850, the final R = 0.0591 and wR = 0.0963 for all data. Complex 2 belongs to triclinic system, space group P1̄, a = 9.6990(7) Å, b = 12.0380(11) Å, c = 14.6060(12) Å, α = 103.274(2)°, β = 93.0930(10)°, γ = 97.4250(10)°, V = 1639.7(2) ų, Z = 1, ρ = 1.764 g/cm³, μ = 2.694 mm⁻¹, F(000) = 854, the final R = 0.0545 and wR = 0.0911 for all data.

The bimetallic mixed-ligand complexes [MHg(C₆H₆ON₂)₂(SCN)₄], where M²⁺ = Co (I), Ni (II), Cu (III), and C₆H₆ON₂ is nicotinamide (NA), have been synthesized from aqueous solutions and studied by chemical analysis and IR spectroscopy. Molecule NA can be either a bridging or bidentate ligand, the thiocyanate ligand is ambidentate, so the crystal structure of the complexes may be either polymeric or molecular. The structure of complexes I and III has been characterized by X-ray diffraction. Crystals are monoclinic, space group C2/c, Z = 8, and a = 26.6385(5) Å, b = 12.8622(2) Å, c = 19.033(4) Å. β = 133.3779(4)°, V = 4739.9 ų, ρ_calcd = 2.063 g/cm³ for complex I, and a = 26.2828(7) Å, b = 12.7435(4) Å, c = 18.9408(9) Å, β = 132.217(1)º, V = 4698.35 ų, ρ_calcd = 2.094 g/cm³ for complex III. The synthesis of single crystals suitable for X-ray diffraction analysis has been failed for the nickel(II) complex, but this compound has been studied by X-ray powder diffraction. The comparison of experimental and calculated X-ray diffraction patterns enables the conclusion about similar structures of the [CoHg(C₆H₆N₂O)₂(SCN)₄] and [NiHg(C₆H₆N₂O)₂(SCN)₄] phases. Crystals of complexes I–III are isostructural. The sulfur atoms of four rhodanide groups form the tetrahedral coordination environment of the mercury atoms. The octahedral coordination environment typical for the cobalt(II) complex becomes tetragonal pyramidal in the case of copper(II). M(NA)₂ units and mercury atoms are linked into a 3D-framework by bridging rhodanide groups.

In this study, natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) analyses have been used to illustrate structure and bonding in iron aminoborirene complex [(η⁵-C₅H₅)(OC)₂Fe{μ-BN(SiH₃)₂C=C}Ph] (closed-isomer) and its isomer boryl complex [(η⁵-C₅H₅)(OC)₂FeBN(SiH₃)₂C≡CPh] (open-isomer). It has been found that the closed isomer has minor stability as compared to the open isomer. Natural bond orbital analysis (NBO), Quantum theory of atoms in molecules analysis (QTAIM), Electron localization function (ELF), and Localized orbital locator (LOL) analyses have been applied to assess the Fe-C and F-B bonds in the complexes.

Previously, a universal relation for the energy and length of homopolar covalent bond has been derived with the use of the theory of generalized charges, which represents an asymptotic approximation for interatomic forces of the quantum-statistical model of a multicomponent electron gas. The article discusses the new implications of the theory, obtained to describe the donor-acceptor bond. The bond energy includes the contribution of the donor atom characteristic of a homopolar bond and the Coulomb interaction of the atoms, with allowance for the probability of fixation of the bond electrons on the acceptor. Regularities for the donor-acceptor bond length and energy have been discovered. In particular, for the particular case realized in hydrides, expressions are obtained for the length and bond energy versus the atomic number of the acceptor.

Using density functional theory, three noncovalent interactions and mechanism of covalent functionalization of drug artemisinin onto γ-Fe₂O₃ nanoparticles have been investigated. Quantum molecular descriptors of noncovalent configurations were studied. It was specified that binding of drug artemisinin with γ-Fe₂O₃ nanoparticles is thermodynamically suitable. Hardness and the gap of energy between LUMO and HOMO of artemisinin drug are higher than those of noncovalent artemisinin-γ-Fe₂O₃ nanoparticle configurations, showing the reactivity of artemisinin increases in the presence of γ-Fe₂O₃ nanoparticles. Artemisinin can bond to γ-Fe₂O₃ nanoparticles through carbonyl group. The activation energies, the activation enthalpies and the activation Gibbs free energies of this reaction were calculated. The activation parameters and thermodynamic data indicate that this reaction is exothermic and spontaneous and can take place at room temperature. These results could be generalized to other similar drugs.

The iron(III) compound of composition [Fe(III)(salen)(2-Me-Him)]_n, where H₂salen = N, N′-ethylenebis(salicylaldimine) and 2-Me-Him = 2-methylimidazolate bridging ligand, was prepared. Magnetic resonance and magnetic susceptibility measurements showed the existence of linear and zigzag antiferromagnetic chains in the compound. Weak ferromagnetism was shown to arise in zigzag antiferromagnetic chains due to antisymmetric exchange interactions. The features of the temperature dependence of magnetization indicate that the magnetic system experiences the transition to the spin-glass state at a temperature below 30 K.

Phase equilibria in the As₂Se₃–InSe system were studied by physicochemical analysis methods (differential thermal, X-ray powder diffraction, and microstructural analyses and microhardness and density measurements), and the phase diagram of the system was constructed. It was found that the system is a quasi-binary section of the ternary system In–As–Se and is characterized by the formation of two ternary selenides, InAs₂Se₄ and In₃As₂Se₆, melting without decomposition at 775 and 810°C, respectively. The coordinates of eutectic points are (13 mol % InSe, 315°C), (80 mol % InSe, 675°C), and (85 mol % InSe, 535°C). The arsenic selenide-based glass-forming range is 20 mol % InSe, and the crystalline-glass range extends to 35 mol % InSe. The solubilities based on As₂Se₃ and InSe are limited and are 5 and 3 mol %, respectively. According to X-ray powder diffraction analysis data, the compounds InAs₂Se₄ and In₃As₂Se₆ crystallize in the tetragonal system with the unit cell parameters a = 9.44 Å, c = 8.73 Å, V = 785.6 ų, Z = 4 and a = 9.42 Å, c = 8.77 Å, Z = 3, respectively.

A possibility to use acid-type phosphoryl-containing podands with diethylene glycol polyether chain, which differ in substituent at the phosphoryl group, as extractants for the recovery of U(VI), Th(IV), and rare earth elements(III) from nitric acid solutions has been studied. Features of the effect of HNO₃ concentration on U(VI) and Th(IV) extraction with solutions of the phosphoryl-containing podands in dichloroethane has been revealed. Uranium(VI) is extracted as a normal intracomplex salt of dibasic acid UO₂L³ with chelate coordination of both POO⁻ groups to one cation. Thorium(IV) produces a complex as a normal intracomplex salt of composition Th(L³)₂ where two bivalent anions of ligand acid are coordinated via all four POO⁻ groups to Th(IV) cation. Sorption of U(VI), Th(IV), and REE(III) by impregnated sorbent based on LPS-500 polymer with 1,5-bis[2-(oxyethoxyphosphoryl-4-ethyl)phenoxy]-3-oxapentane from 0.052 and 3.52 mol/L HNO₃ has been studied. It has been established that the obtained sorbent shows high selectivity in the separation of U(VI), Th(IV), and REE(III). The separation factor for uranium(VI) and europium(III) (β_U/Eu) has been found to be 202 and ∼55000 upon sorption from 3.52 and 0.052 mol/L HNO₃, respectively, at V/m = 500 mL/g. At thorium(IV) sorption from 3.52 and 0.052 mol/L HNO₃, β_Th/U = 66 and ∼5050, respectively.

Dissociation and complexation with Cu(II) cation is studied for phosphoryl-containing podands (tetrabasic 1,5-bis[2-(dioxyphosphoryl)-4-ethylphenoxy]acidic-type-3-oxapentane (H₄L^P) and dibasic 1,5-bis[2-(oxyethoxyphosphoryl)-4-ethylphenoxy]-pentane (H₂L^P)) and their carbonyl analog (polyether dibasic acid 1,5-bis[2-(oxycarbonylphenoxy)]oxapentane (H₂L^C) in water in the presence of 5% dimethylformamide potentiometrically, spectrophotometrically, and conductometrically. Phosphoryl podands exhibit good complexing properties and can selectively bind metal cations. The dissociation constants are determined and the distribution diagram of ionized species of the compounds under study depending on pH is plotted. The molar ratio between the metal and podand in all complexes is found to be 1 : 1. The stability constants of complexes with Cu²⁺ cation are calculated. The most stable copper(II) complexes are formed with the tetrabasic podand.