Vol 63, No 7 (2018)

To expand the range of precursors used in the sol–gel technology for applying nanostructured SnO₂ thin films promising as components of semiconductor chemical gas sensors, the efficiency of using tin acetylacetonate solutions with various precursor concentrations was demonstrated. It was determined that finely divided SnO₂ with a crystallite size of 3–4 nm (cassiterite) can be obtained by hydrolysis by atmospheric moisture in the course of solvent evaporation at room temperature. Using tin acetylacetonate solutions with various precursor concentrations for applying SnO₂ thin films by dip coating to the surface of rough ceramic Al₂O₃-based substrates with platinum interdigital electrodes and a microheater resulted in significant differences in microstructure, continuity, thickness, and porosity of the produced coatings. In a lower-concentration (0.13 mol/L) tin acetylacetonate solution, a multilayer dense continuous SnO₂ coating was applied, whereas in a higher-concentration (0.25 mol/L) solution, the formed layer comprised aggregated nanoparticles 30–60 nm in size and had much more defects and higher porosity. The sensitivity of the obtained thin-film nanostructures to the most practically important gaseous analytes: CO, H₂, CH₄, CO₂, and NO₂. The produced two-dimensional nanomaterials were shown to be promising for detecting carbon monoxide at 200–300°C in dry air.

Tri-p-tolylbismuth perchlorate (1) and μ-oxo-bis[(perchlorato)tri-p-tolylbismuth] (2) have been synthesized by the reaction between tri-p-tolylbismuth dibromide and silver perchlorate and its hydrate. The complexes have been studied by chemical analysis, IR spectroscopy, and X-ray diffraction. Complex 1 is triclinic, space group Pī, Z = 4, a =10.7271(9) Å, b = 13.5585(11) Å, c = 18.1592(13) Å, α = 110.867(3)°, β = 94.944(3)°, γ = 96.888(3)°, V = 2426.3(3) Å3, ρ_calcd = 1.865 g/cm3; complex 2 crystallizes in trigonal symmetry, space group R\(\bar 3\), a = 13.1157(2) Å, c = 22.1959(2) Å, γ = 120°, V = 3306.64(8) ų, ρ_calcd = 1.777 g/cm³. The bismuth atoms in the molecular structure of complex 1 have a distorted trigonal bipyramidal coordination to the apically arranged oxygen atoms of perchlorate ions (Bi–C, 2.180(5)–2.201(5) Å; Bi–O, 2.324(4)–2.355(4) Å; OBiO axial angles, 170.1(1)°, 174.5(1)°). The structure of complex 2 contains binuclear [p-Tol₃Bi(ClO₄)]₂O molecules (Bi–O, 2.371(15), 1.9107(7) Å; OBiO axial angle, 180.0°).

Five novel metal coordination compounds with (Z)-4-(2-hydroxy-5-nitrophenyl)hydrazono-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (H₂L) have been prepared and isolated in crystalline state. Crystal and molecular structure of H₂L have been established by X-ray diffraction study. A molecule of the organic compound exists in crystal state as a nearly flat hydrazo tautomer stabilized by intramolecular hydrogen bonds. Metal coordination is tridentate chelate, which has been confirmed by IR, electronic, ¹H NMR, and EPR spectroscopy and DFT/B3LYP quantum chemical modeling. Coloristic and fungicidal properties of H₂L and its metal complexes have been studied.

Complex [Zn(Tsc)₂](Nds) · H₂O (I) (Tsc is thiosemicarbazide, NH₂NHC(=S)NH₂, and 1,5-Nds₂–is the double-deprotonated anion of 1,5-naphthalenedisulfonic acid, C₁₀H₆(SO₃)₂^2-) has been synthesized and studied by IR spectroscopy, thermogravimetry, and X-ray diffraction analysis. The structural units of crystal I are complex cations [Zn(Tsc)₂]²⁺, anions (Nds)^2–, and crystallization water molecules. The Zn atom is coordinated along the vertices of the distorted tetrahedron by two sulfur atoms and two nitrogen atoms of two bidentate chelate (S,N) Tsc ligands. The structural units of crystal I are joined together by a branched network of the N–H···O hydrogen bonds involving independent donor hydrogen atoms of the NH₂ and NH groups of Tsc molecules (nine of ten, except for the H(6A) atom), all six independent acceptor oxygen atoms of the SO₃ groups of the Nds^2– anions, and two acceptor hydrogen atoms and one donor oxygen atom of the water molecule.

A new complex of composition [Cu(DMSO)₄SiF₆] (I), where DMSO is dimethyl sulfoxide (CH₃)₂SO, has been prepared and characterized by X-ray diffraction. Crystals I are triclinic, space group P\(\bar 1\), Z = 2, a = 10.1772(4) Å, b = 10.3061(5) Å, c = 10.6071(5) Å, V = 1003.94 Å3, ρ_calc = 1.714 g/cm³.

Computational modeling of borospherene B₃₂ complexes with nitrogen has been performed by the density functional theory method (DFT UB3LYP*/6-311+G(d)). The geometry of isomers of these complexes with a different starting orientation of N has been found, their relative energies have been calculated, and the spin density distribution has been studied. Computation results predict that the structures with a nitrogen atom or ion built into the boron cage are more favorable than the endohedral isomers.

The bond angles in the macrocycles of tetrathio- and dioxodithio-substituted 1,8-dioxa-3,6,10,13-tetraazacyclotetradecanes and their Cr(II), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes with the (NNNN) coordination of the ligand donor sites, formed upon the complexation in the ternary systems M(II)–ethanedithioamide H₂N–C(=S)–C(=S)–NH₂ (thiocarbamoylmethanamide H₂N–C(=S)–C(=O)–NH₂)–formaldehyde H₂C(=O) in gelatin-immobilized matrix implants have been calculated by the DFT OPBE/TZVP method with the Gaussian 09 program package. It has been stated that, depending on the nature of M(II) and macrocyclic ligand, the complexation can lead to both the decrease and the increase in the degree of macrocycle distortion (quantatively characterized as the degree of deviation of the macrocycle from coplanarity).

Physicochemical study of cis-[Pt(NH3)2Cl2] and cis-[Pt(NH₃)₂Cl₂(OH)₂] is carried out, and immobilization of platinum complexes on the nanoporous carbon substrate is investigated. The solubility of cis-[Pt(NH₃)₂Cl₂] in 1 M HCl solution is determined, and the average enthalpy of dissolution is calculated: Δ_solH° = 27.3 ± 0.9 kJ/mol. The batch capacity is determined experimentally for cis-[Pt(NH3)2Cl2] and cis- [Pt(NH₃)₂Cl₂(OH)₂] to be 32.9 mg/g (0.17 mg-equiv/g) and 47.6 mg/g (0.24 mg-equiv/g), respectively. Immobilization of platinum complexes on the oxidized carbon surface is found to take place due to interaction between carboxy groups and ammine groups of platinum complexes. The resulting heat capacity curves are used to calculate the enthalpies of adsorption for cis-[Pt(NH₃)₂Cl₂] and cis-[Pt(NH₃)₂Cl₂(OH)₂] on the oxidized carbon surface, equal to 24.46 and 27.46 kJ/mol, respectively.

The phase complex of the system Na,K,Mg,Ca∥SO₄,Cl–H₂O at 50°С in the 2MgCl₂ · CaCl₂ · 12H₂O and CaCl₂ · 2H₂O crystallization fields has been predicted and constructed using the translation method. 2MgCl₂ · CaCl₂ · 12H₂O and CaCl₂ · 2H₂O are involved in the formation of the following numbers of geometric images of the title system: three and one invariant points; 10 and 4 monovariant curves; and 12 and 6 divariant fields, respectively. The phase complex of the title system has been fragmented into divariant fields.

Phase equilibria were experimentally studied in the system LiF–KI–KF–K₂CrO₄, which is the stable tetrahedron of the quaternary reciprocal system Li, K∥F, I, CrO₄. Differential thermal analysis revealed the compositions and transformation temperatures at the eutectic point E^□ 488 (L ⇄ LiF + KF + KI + α-K₂CrO₄) and the peritectic point P^□ 510 (L + K₃FCrO₄ ⇄ KI + α-K₂CrO₄ + KF). A computer model of the phase complex of the system was built, which can predict phase transformations at an arbitrary composition in the system. Isothermal sections of the systems were constructed, using which the phase composition at the temperature of the section can be calculated.

A computer phase diagram model is constructed for the MgO–SiO₂–Al₂O₃ system, giving its complete geometric description and containing 10 liquidus surfaces, a liquid–liquid phase separation surface, 75 ruled surfaces at the boundaries between two-phase and three-phase fields, 11 horizontal four-simplex at invariant temperatures, 21 two-phase fields, and 30 three-phase fields. The description of surfaces and three-phase fields is presented.

Certain equilibria involving polymeric gold(I) thiomalate complexes have been studied by spectrophotometry and pH measurements in aqueous solution at 25°С and I = 0.2 M (NaCl). Thiomalate protonation constants H_i–1Tm^3– + H⁺ = HiTm^i–3 have been found to be logK_H1 = 10.23, logK_H2 = 4.51, logK_H3 = 3.01. Efficient functions have been used to allow for multiple protonation of polymeric complexes Au_n Tm_m^{n-3 m} Equilibrium constants for reactions Au₄Tm₄⁸⁻ + Tm^3– = Au₄Tm₅¹¹⁻ (logK₄₅ = 10.1 ± 0.5) and 0.25 Au₄Tm₄⁸⁻ + Tm^3– = AuTm₂⁵⁻ (logK₁₂ = 4.9 ± 0.2) have been determined. Standard potential for AuTm²⁵⁻ has been found to be equal to E_1/0⁰ =–0.260 ± 0.025 V.

The complexation of 3-substituted-2-(aryl-,methyl)sulfonylamino-4,5,6,7-tetrahydrobenzo[ b]thiophenes with Cu(II), Co(II), and Ni(II) ions in ammonia media was studied. Different types of complexes with Cu(II) ions were found depending on pH: with a ratio of 1: 2 at pH of ~4–5 and 1: 1 at pH of ~ 8–10. For the Co(II) and Ni(II) ions, the formation of 1: 1 complexes at pH of ~9–10 was established. The Cu(II), Co(II), and Ni(II) complexes [Cu(HL)₂. 2H₂O] and [ML. 2H₂O] were separated and identified, and their solubility products were calculated. The effect of the nature of the functional group in the third position of the thiophene ring on the properties of the complexes of reagents with nonferrous metal ions was shown.