Structure and energy studies of Β-diketonates. 4. vibrational characteristics of Y(DPM)3 and Y(DPM)2

The vibrational problem for the Y(DPM)₃ and Y(DPM)₂ molecular forms that are present in the overheated vapor of yttrium tris-dipivaloylmethanate is solved. For this purpose, the experimental Raman spectra of Y(DPM)₃ solutions are interpreted. The force field of the Y(DPM)₂ radical is estimated on the basis of the force constants determined for Y(DPM)₃. Rms vibrational amplitudes and corrections for perpendicular displacements to the internuclear distances of the two molecular forms needed for interpreting electron diffraction data are calculated. Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 3, pp. 470–479, May–June, 1997.     

Phthalazone arylhydrazones

The products of the reaction of 1-chloro- and 1, 4-dichlorophthalazine with nitrophenylhydrazines are the E isomers of the nitrophenylhydrazones of the corresponding phthalazone. 2-Methyl-4-chlorophthalazone 4-nitrophenylhydrazone was found to be a mixture of Z and E isomers (32). 1, 4-Dichlorophthalazine reacts with 1-methyl-1-phenyl- and 1, 1-diphenylhydrazines to give monosubstitution produdcts, for which the phthalazone hydrazone (III) or phthalazinylhydrazine (VI) form or a tautomeric mixture of III and VI is realized, depending on the nature of the solvent and other factors. Some oxidation, reduction, and nucleophilic substitution reactions of the compounds obtained are examined.Communication LX from the series Hydrazones. See [1] for communication LIX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 699–707, May, 1978.     

Five-membered 2,3-dioxo heterocycles: LVI. Reaction of 3-aroyl-1<Emphasis Type="Italic">H</Emphasis>-pyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzoxazine-1,2,4-triones with acyclic enamino ketones

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones react with 4-arylaminopent-3-en-2-ones and 3-amino-1,3-diphenylprop-2-en-1-ones to give substituted 4-aroyl-3-hydroxy-1-(o-hydroxyphenyl)-1,7-diazaspiro[4.4]nona-3,8-diene-2,6-diones.     

Tautomeric properties and gas-phase structure of 3-chloro-2,4-pentanedione

The tautomeric properties of alpha-chlorinated acetylacetone, 3-chloro-2,4-pentanedione CH3C(O)-CHCl-C(O)CH3, have been investigated by gas electron diffraction (GED) and quantum chemical calculations (B3LYP and MP2 approximations with different basis sets up to cc-pVTZ). Analysis of the GED intensities resulted in the presence of 100(2)% enol tautomer at 269(8) K. The following skeletal geometric parameters (rh1 values) of the molecule, which possesses Cs symmetry, were derived: r(C=C) = 1.378(3) A, r(C-C) = 1.450(3) A, r(C=O) = 1.243(3) A, r(C-O) = 1.319(3) A, r(O-H) = 1.001(4) A, r(C-Cl) = 1.752(4) A, angleC-C=C = 121.3(1.0) degrees , angleC=C-O = 119.9(1.2) degrees , angleC-C=O = 119.1(1.2) degrees . Due to very small contributions of the keto tautomer in alpha-chlorinated acetylacetone and its parent species, the effect of alpha-chlorination on tautomeric properties cannot be derived from experimental data. Quantum chemical calculations (B3LYP/6-31G**, B3LYP/cc-pVTZ, and MP2/cc-pVTZ) predict that alpha-chlorination of acetylacetone has no pronounced effect on the tautomeric properties. On the other hand, similar calculations for 1-chloro-1,3-butanedion, ClC(O)-CH2-C(O)CH3, demonstrate that chlorination in one beta position destabilizes the enol tautomer. In both chlorinated species the enol form is strongly preferred.     

The structure of particles of the dispersed phase in europium oxyhydroxide hydrosol

Russian Chemical Bulletin - Rheological studies revealed the formation of boundary layers of oriented water dipoles on the surface of particles of the dispersed phase in europium oxyhydroxide...     

Unusual Behavior of Nitrogen-Containing Organosilicon Compounds in the Reactions with Isocyanates

Russian Journal of General Chemistry - The behavior of organic and organosilicon nitrogen-containing compounds such as N-(trimethylsilyl)N-(2-{2-[(trimethylsilyl)oxy]ethoxy]}ethyl)amine and...     

Spectroelectrochemical Properties and Catalytic Activity in Cyclohexane Oxidation of the Hybrid Zr/Hf-Phthalocyaninate-Capped Nickel(II) and Iron(II) tris-Pyridineoximates and Their Precursors

The in situ spectroelectrochemical cyclic voltammetric studies of the antimony-monocapped nickel(II) and iron(II) tris-pyridineoximates with a labile triethylantimony cross-linking group and Zr(IV)/Hf(IV) phthalocyaninate complexes were performed in order to understand the nature of the redox events in the molecules of heterodinuclear zirconium(IV) and hafnium(IV) phthalocyaninate-capped derivatives. Electronic structures of their 1e-oxidized and 1e-electron-reduced forms were experimentally studied by electron paramagnetic resonance (EPR) spectroscopy and UV−vis−near-IR spectroelectrochemical experiments and supported by density functional theory (DFT) calculations. The investigated hybrid molecular systems that combine a transition metal (pseudo)clathrochelate and a Zr/Hf-phthalocyaninate moiety exhibit quite rich redox activity both in the cathodic and in the anodic region. These binuclear compounds and their precursors were tested as potential catalysts in oxidation reactions of cyclohexane and the results are discussed.     

Maghemite nanocrystal impregnation by hydrophobic surface modification of mesoporous silica

Here, we report the design of a hybrid inorganic/organic mesoporous material through simultaneous pore engineering and hydrophobic surface modification of the intramesochannels to improve the uptake of superparamagnetic maghemite nanocrystals via impregnation techniques. The mesoporous material of the SBA-15 type was functionalized in situ with thiol organo-siloxane groups. Restricting the addition of the thiol organo-siloxane to 2 mol % yielded an inorganic/organic hybrid material characterized by large pores and a well-ordered hexagonal p6mm mesophase. The hydrophobic surface modification promoted the incorporation of 7.5 nm maghemite (gamma-Fe2O3) nanocrystals, prepared through temperature-controlled decomposition of iron pentacarbonyl in organic solvents. The hydrophobic, oleic acid capped superparamagnetic maghemite nanocrystals were incorporated into the porous network via wet impregnation from organic suspensions. Combining diffraction, microscopy, and adsorption data confirmed the uptake of the nanocrystals within the intramesochannels of the silica host. Magnetization dependencies on magnetic field at different temperatures show a constriction in the loop around the origin, which indicates immobilization of maghemite nanocrystals inside the thiol-functionalized silica host.     

Effect of phosphate doping on electric properties and chemical stability of Ba<Subscript>4</Subscript>Ca<Subscript>2</Subscript>Nb<Subscript>2</Subscript>O<Subscript>11</Subscript> protonic conductor

Conductivity of perovskite phosphate–substituted solid solutions of Ba₄Ca₂Nb_{2 –x} P _x O₁₁ (0.0 ≤ x ≤ 0.5) was studied as a function of temperature, partial pressure of oxygen and water vapors. It is proved that the studied systems are protonic conductors at the temperatures below 600°C in the atmosphere with elevated content of water vapors (pH₂O = 1.92 × 10^–2 atm). Introduction of the tetrahedral [PO₄] group in the complex oxide matrix of Ba₄Ca₂Nb₂O₁₁ results in an increase in the oxygen–ionic (dry air, pH₂O = 1.91 × 10^–4 atm) and protonic conductivities (wet air, pH₂O = 1.92 × 10^–2 atm). Is it found that the doping causes a considerable increase in chemical stability of phases with respect to carbon dioxide.     

Effect of F<Superscript>–</Superscript>-doping on the transport properties of perovskite-like complex oxides

The structural and electric characteristics of fluorine-substituted complex oxides obtained by anion doping based on Ba₂CaNbO_5.5 and Ba₂In₂O₅ matrices were compared. The mobility of ion charge carriers was found to depend on the concentration of the dopant anion and oxygen vacancies and the degree of disordering of the latter.