Том 86, № 10 (2016)

Reactions of gas-phase synthesis of lead phosphates and tellurates have been studied. Standard enthalpies of formation and atomization of gaseous PbPO₂, PbPO₃, PbP₂O₆, PbTeO₃, and Pb₂TeO₄ salts have been determined.

The features of formation of a two-component phosphorus-titanium oxide coating on the silica surface by sequential treatment of the substrate with POCl₃ and TiCl₄ vapors were analyzed with application of quantum-chemical approaches. An experimental synthesis of two-component coatings under conditions selected on the basis of theoretical calculations yielded coatings whose composition corresponded to the model predictions. The structure of the resulting coatings was studied by Fourier-transform IR spectroscopy, electronic diffuse reflectance spectroscopy, and chemical analysis.

The sequence of phases appearance during the formation of Bi_1–xNd_xFeO₃ solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO₃ or NdFeO₃) is essential for the realization of the series of phase transformations yielding solid solutions of multiferroics Bi_1–xNd_xFeO₃ as the final product, due to the prevalence of various interphase contacts in the starting reaction zone.

Using the tandem mass-spectrometry method, the experimental evidence have been obtained that an important component of electron ionization mass spectra of monofunctional compounds RX (X being a functional group) is the alkene subspectrum, including peaks of fragment ion [R–H]^+· and products of its fragmentation.

The reaction of gem-dichloro- and gem-dibromocyclopropanes with n-butyllithium in THF under argon at–78°С followed by purging the reaction mixture with dry CO₂ was used to synthesize cis- and/or trans-1-halocyclopropane-1-carboxylic acids in 30–56% yields. The yields of the target products could be increased to 76–83% by the addition of an equimolar amount of LiCl to the reaction mixture. The highest salt effect was obtained with lithium chloride generated in situ (88–96%).

Regioselectivity of the methanolysis of lower polychlorinated biphenyls with sodium methoxide in a mixture of methanol and DMSO at 100–130°С was studied. It was found that 2,4,4'-tricholobiphenyl is much more reactive than 2,4-dichlorobiphenyl. This results in different mechanisms of substitution. 2,4-Dichlorobiphenyl reacts with sodium methoxide by the elimination–addition mechanism to form four monosubstitution products in comparable quantities. 2,4,4'-Trichlorobiphenyl reacts with the methodixe ion by the classical SNAr mechanism, with preferential substitution of the 2-chlorine atom.

Reactions of ethoxymethylidenemalonate with malonic acid N-arylamidoesters in the presence of triethylamine afforded diethyl 1-aryl-6-hydroxy-2-oxo-1,2-dihydropyridine-3,5-dicarboxylates via the cyclization of Michael adducts. In the presence of sodium ethoxide the formed adducts may be also involved into simultaneous retro-Michael reaction leading to the formation of ethyl 1-aryl-5-arylcarbamoyl-6-hydroxy-2-oxo-1,2-dihydropyridine-3-carboxylates. Direction of heterocyclization or retro-Michael reaction is determined by the acidity of the hydrogen atoms of adducts and basicity of catalyst.

The electronic structure and features of interatomic interactions providing the Si–O–C₆H₅ bonds in H_4-nSi(OC₆H₅)_n (n = 1–4) were studied by a combined analysis of the X-ray emission and photoelectron spectroscopic data and the results of quantum-chemical calculations. Theoretical calculations were carried out using the density functional theory. The distributions of the density of states were constructed, the correlation energy diagrams were presented, and the main types of interatomic interactions in phenoxysilanes were revealed.

The reaction of tetrachloroauric acid hexahydrate with (4-fluorobenzyl)triphenylphosphonium and (buten-2-yl)triphenylphosphonium (1:1, mol) chlorides results in the formation of the [Ph₃P(4-FC₆H₄CH₂)]⁺ [AuCl₄]^– and [Ph₃PCH₂CH=CHMe]⁺[AuCl₄]^– complexes. Structure of the complexes was studied by the X-ray diffraction (XRD) analysis.

Parameters of the solvation equilibria \({\left[ {Fe{{\left( {{H_2}O} \right)}_6}} \right]^{3 + }} + nDMSO \rightleftarrows {\left[ {Fe{{\left( {{H_2}O} \right)}_{6 - n}}{{\left( {DMSO} \right)}_n}} \right]^{3 + }} + n{H_2}O\) have been determined in aqueous-dimethyl sulfoxide solutions (0–90 vol% DMSO) by means of spectrophotometry and mathematical modeling of equilibria. Iron(III) is not involved in the complex formation with derivatives of sym-triazine: 2,4-diamino-6-(carbamoylmethylsulfinylmethyl)-1,3,5-triazine and 2,4-diamino-6-(acetohydrazidomethylsulfinylmethyl)-1,3,5-triazine in aqueous DMSO medium (40 vol % DMSO). Bis(hydrazinocarbonylmethyl) sulfoxide forms two complexes with iron(III), with 1: 1 and 1: 2 compositions; in contrast to the Cu(II) and Ni(II) complexes, in the iron complexes the ligand exists in the amide form. The most probable structures of the complexes have been revealed by molecular mechanics simulation and (in selected cases) using the DFT/B3LYP/6-31++G(d,p) density functional theory method.

Molecular complexes of bis(4-formyl-3-methyl-1-phenyl-1H-pyrazol-5-olato)cadmium(II) with isoquinolin-1-amine, quinolin-3-amine, 4,6-dimethylquinolin-5-amine, and quinolin-6-amine have been synthesized, and their structure was studied by IR, UV, ¹H NMR, and X-ray absorption spectroscopy. Photoluminescence properties of the complexes have also been examined.