Том 61, № 6 (2016)

Hydroxyapatite nanoparticles (NPs) were prepared by controlled precipitation in the presence of stabilizers that confined growth and inhibited the aggregation of nanoparticles. Electrostatically stabilized NPs were prepared in the presence of sodium citrate; Tween 80 was used for steric stabilization. At low stabilizer concentrations, nanorods were formed of grown together, spheroidal hydroxyapatite NPs of ~20 nm in diameter. The rod length decreased as ether sodium citrate or Tween 80 concentration increased. When Cit^3–/Ca²⁺ = 3mol/mol, platelike NPs were formed 20–45 nm long and ~10 nm wide; for Cit^3–/Ca²⁺ = 4 mol/mol, NPs had sizes of 10–15 nm. At relatively high Tween 80 concentrations (>0.05 mol/L), foamlike structures were obtained.

The synthesis of binuclear ruthenium(IV) oxochloride complex and reaction of the latter with LiCl in a 2.5 M HCl solution have been carried out. The reaction of Ru(IV) binding in solution leads to the formation of a new cluster compound Li₈Ru₂OCl₁₄ (I) whose molecular structure has been determined by X-ray diffraction. The crystals are tetragonal, space group \(I\bar 42m\), a = 7.08 Å, c = 17.00 Å, V = 852.18 ų, Z = 2. Supramolecular structural self-organization of I includes the formation of layers parallel to the xy plane. The high thermal stability of complex I and retention of its dinuclear structure in an acidic environment have been shown by thermal analysis and IR and electronic spectroscopy. It has been found that cluster I is an efficient catalyst for water oxidation in artificial photosynthesis.

Optimal conditions for the synthesis of Sm₂Sn₂O₇ with pyrochlore crystal structure by solid-phase reactions were determined. The effect of temperature (346–1050 K) on the molar heat capacity of samarium stannate was studied by differential scanning calorimetry. Thermodynamic properties of Sm₂Sn₂O₇ in the temperature range under study were determined using the experimental data.

Tri(meta-tolyl)antimony chloro(benzenesulfonate) (I) has been synthesized by the reaction between tri(meta-tolyl)antimony bis(benzenesulfonate) and tri(meta-tolyl)antimony dichloride (toluene; 0.5 h, 100°C). According to X-ray diffraction data, the antimony atoms in two crystallographically independent molecules Ia and Ib have a distorted trigonal bipyramidal coordination to chlorine and oxygen atoms in axial positions: OSbCl, 177.8(4)° (Ia), 178.6(4)° (Ib); CSbC, 114.0(9)°‒127.6(8)° (Ia), CSbC, 114.4(8)°‒128.0(8)° (Ib); Sb‒C, 2.01(2)‒2.139(18) Å, Sb‒Cl, 2.453(7) Å, Sb‒O, 2.163(13) Å (Ia), Sb‒C, 2.07(2)‒2.14(2) Å, Sb‒Cl, 2.442(7) Å; Sb‒O, 2.187(14) Å (Ib).

Twenty two new complexes of some tervalent metals (aluminum, chromium, iron, and lanthanides) with nitrozohydroxylamine N-alkyl(benzyl) derivatives ML₃^m · nH₂O, (m = 1‒5) were synthesized and isolated in a crystalline state. The crystal and molecular structures of the iron(III) complex with N-(2-fluorobenzyl)-N-nitrozohydroxylamine were determined by X-ray diffraction. An octahedral coordination of the central ion and a bidentate chelating coordination of the organic ligand were established. The spectral criteria of coordination of nitrozohydroxylamine alkyl(benzyl) derivatives were determined, and the complexation processes in solutions were studied.

The successive elimination of Н₂ from a NaBH₄ molecule surrounded by a few (up to eight) water molecules has been modeled in the framework of the cluster approach with the use of the 6-31G* basis set and hybrid density functional (B3LYP). Computations show that the elimination of the hydrogen molecule from the NaBH₄ · nH₂O complex occurs through the coupling of Н^– and Н⁺ ions from BH₄⁻ and Н₂О, respectively, to form intermediate ВН₃ and ОН^– species separated by water molecules. Proton transfer occurs along a hydrogen bond chain through a relay mechanism. The elimination of the remaining hydrogen atoms to convert the BH₄⁻ anion into B(OH)₄⁻ proceeds analogously but with lower barriers.

The thermal behavior of the molybdenum(VI) complex with N-isopropylhydroxylamine [MoO₂(i-C₃H₇NHO)₂] has been studied. The thermal decomposition of the complex has been found to proceed in a single stage at 185.5°C and to result in non-stoichiometric molybdenum(IV) dioxide.

Single crystals of CsNbMoO₆ were grown from solution in melt, and their crystal structure was solved by X-ray diffraction (R[I > 2σ(I)]₁ = 0.0386). Crystals were cubic, а = 10.41039(8) Å, Z = 8, space group \(F\bar 43m\). The synthesized crystals were shown to exhibit the second harmonic generation effect, which confirmed the absence of an inversion center in the structure. The structure was built of MO₆ (M = Nb, Mo) octahedra, which share all vertices to form a three-dimensional framework where niobium and molybdenum atoms are randomly distributed. Framework interstices accommodate cesium ions. Crystals of CsNbMoO6 can be considered as pseudo-symmetric with respect to space group \(Fd\bar 3m\) due to a small shift of some oxygen atoms relative to the regular system of points in this group.

The solubility in the quaternary water–salt system Zr(SO₄)₂ · 4Н₂О–Na₂SO₄–H₂SO₄–H₂O at 25°C was studied. It was found that, in the system, there is crystallization of not only Na₂SO₄ and Zr(SO₄)₄ · 4H₂O, but also sodium sulfate zirconates Na₂Zr(SO₄)₂(OH)₂ · 0.3H₂O, Na₄Zr(SO₄)₄ · 3H₂O, and Na₂Zr(SO₄)₂ · 3H₂O and two new compounds, S₁ and S₂, which are presumably Na₂ZrO(SO₄)₂ · 2H₂O and Na₂Zr₂O₂(SO₄)₃ · 6H₂O.

The complexation reactions between La³⁺, Y³⁺ and Ce³⁺ cations with the macrocyclic ligand, kryptofix 21, were studied in methanol-acetonitrile (MeOH-AN) and methanol-methylacetate (MeOHMeOAc) binary mixed solvent solutions at different temperatures using the conductometric method. The conductance data show that in most solvent systems, the kryptofix 21 forms a 1: 1 [M: L] complex with La³⁺, Y³⁺ and Ce³⁺ metal cations, but in the case of Y³⁺ cation in pure methylacetate, in addition of formation of a 1: 1 [ML] complex, 1: 2 [ML₂] and 1: 3 [ML₃] complexes are formed in solution. In the case of Ce³⁺cation, a 1: 1 [ML] and also a 1: 2 [ML₂] complexes are formed in this solvent system at all studied temperatures. The electrical conductance data in acetonitrile, show that a 1: 1 [ML] and also a 1: 2 [ML₂] complexes are formed between the ligand and La³⁺ and Ce³⁺ metal cations at different temperatures. The stability constants of the 1: 1 [ML] complexes were determined using the conductometric data and a computer program, GENPLOT. A non-monotonic relationship was observed between log_Kf of the 1: 1 complexes with the composition of the binary solvent solutions which was discussed in term of solvent-solvent interactions and also preferential solvation of the metal cations and the ligand in solutions. The selectivity order of the ligand for the metal cations in MeOH–AN and MeOH–MeOAc binary solvent solutions, at 25°C was found to be: Y³⁺ > La³⁺ > Ce³⁺ and La³⁺ > Y³⁺ > Ce³⁺, respectively. The values of the standard thermodynamic quantities (ΔH_c^° and ΔS_c^°) for formation of the 1: 1 complexes were obtained from temperature dependence of the stability constans of the complexes and the results show that the thermodynamics of the complexation reactions between kryptofix 21 and La³⁺, Y³⁺ and Ce³⁺ cations, is affected by the nature and composition of the mixed solvents systems.