[2,6(9)-B10H8>(O)2CCH3]− and [2,7(8)-B10H8(OC(O)CH3)2]2− derivatives in synthesis of position isomers of the [B10H8(OC(O)CH3)(OH)]2− anion with the 2,6(9)- and 2,7(8)-arrangement of functional groups

The interaction of Cat₂B₁₀H₁₀ (Cat = Ph₄P⁺, Ph₄As⁺) with acetic acid has been studied. Disubstituted closo-decaborate derivatives with a bidentately bound acetate group, Cat[2,6(9)-B₁₀H₈>(O)₂CCH₃], or two monodentate acetate groups, Cat₂[2,7(8)-B₁₀H₈(OC(O)CH₃)₂], have been isolated (Cat = Ph₄P⁺, Ph₄As⁺). Hydrolysis of these compounds has led to the position isomers of the [B₁₀H₈(OC(O)CH₃)(OH)]^2? anion with the hydroxo and acetate groups in the 2,6(9)- and 2,7(8)-positions. The structures of {Pb(Bipy)₂[2,6(9)-B₁₀H₈(OC(O)CH₃)(OH)]}₂ · 3H₂O, (Ph₄As)₂[2,6(9)-B₁₀H₈(OC(O)CH₃)(OH)] · 0.4C₂H₅OH · 0.25H₂O, and (Ph₄As)₂[2,7(8)-B₁₀H₈(OC(O)CH₃)(OH)], as well as of the product of the reaction of the B₁₀H ₁₀ ^2? anion with formic acid (Ph₄P)₂[2-B₁₀H₉OC(O)H] · CH₃CN, have been determined by X-ray crystallography.     

Copper(I) coordination compounds with closo-dodecaborate anion

Copper(I) complexes with a closo-dodecaborate anion were synthesized: Cat[CuB₁₂H₁₂], where Cat = Cs⁺, Ph₄P⁺, Ph₄As⁺, or R _x NH _4?x ⁺ (R = Me, Et, Pr, or Bu; x = 3 or 4). The complexes were synthesized from the copper(II)-closo-dodecaborate-sulfur dioxide (sodium sulfite) system. The structure of [Cu₂(NCCH₃)₄B₁₂H₁₂] was determined using X-ray crystallography.     

Solvability of the inhomogeneous Cauchy–Riemann equation in projective weighted spaces

We establish an analog of Hörmander’s Theorem on solvability of the inhomogeneous Cauchy–Riemann equation for a space of measurable functions satisfying a system of uniform estimates. The result is formulated in terms of the weight sequence defining the space. The same conditions guarantee the weak reducibility of the corresponding space of entire functions. Basing on these results, we solve the problem of describing the multipliers in weighted spaces of entire functions with the projective and inductive-projective topological structure. Applications are obtained to convolution operators in the spaces of ultradifferentiable functions of Roumieu type.     

XPS study of fluorinated carbon multi-walled nanotubes

Arc-produced carbon multi-walled nanotubes (MWNTs) were fluorinated at 420 °C in a flow of diluted F₂ gas containing small admixture of HF gas. Fluorinated materials (F-MWNTs) with 10–55 wt.% fluorine content were studied by XPS. It was shown that fluorination begins at the external layers of nanotubes and the reaction front propagates inside the multi-layer particles in concert with structural deterioration of graphene layers. The C₂F stoichiometry still allows MWNT wall integrity, similar to known for SWNTs. The fluorine contents in the product can noticeably exceed this higher fluorine limit for tube stability. The position of the F 1s line at 688.2 eV does not depend on the fluorine concentration. Nearly covalent C–F bonds dominate the F-MWNT samples, with a small quantity (2–9%) of ionic bonds also present. Fluorinated carbon tends to spatially separate from non-fluorinated carbon.     

Influence of the redox state of the ligand on the dealkylation of substituted methylcobaloximes in the presence of heavy metal ions

The synthesis of cobaloxime and methylcobaloxime containing sterically hindered 2,6-di-tert-butylphenol fragments in the ligand is described. Spectral studies of the demethylation of methylbis(dimethylglyoximato)cobalt (1a), methylbis(diphenylglyoximato)cobalt (1b), methylbis[methyl-(3,5-di-tert-butyl-4-hydroxyphenyl)glyoximato]cobalt (1c) pyridinates were carried out in the presence of Cd²⁺, Hg²⁺, Sn⁴⁺, Pb²⁺, and Pb⁴⁺ ions, The free radical forms of the complexes containing a phenoxy radical W the ligand are formed during oxidation. The ESR spectra are given. The unpaired electron in the periphery of the methylcobaloxime ligand1c interacts with the Co-CH₃ fragment through the conjugated systems, enhancing the donating properties of the equatorial ligand of the complex, which leads to the rapid cleavage of the Co-C bond. Therefore the demethylation of methylcobaloxime in the presence of heavy metal ions occurs in a significantly shorter time.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp, 1822–1827, July, 1996.     

Crystal structure of the reaction product of copper(II) nitrate with α-(3,3-Dimethyl-3,4-dihydro-1-isoquinolyl)hydroxy-iminoacetonitrile [Cu3(μ3-OH)(μ-L)3(NO3)2(H2O)] · 2H2O

The coordination compound [Cu₃(μ₃-OH)(μ-L)₃(NO₃)₂(H₂O)] · 2H₂O (I), where L is the α-(3,3-dimethyl-3,4-dihydro-1-isoquinolyl)hydroxyiminoacetonitrile anion, has been synthesized. The crystal and molecular structure of I was determined by X-ray diffraction (Enraf-Nonius CAD4, MoK _α radiation, graphite monochromator, ω-scan mode, 2θ_max = 49.96°, 7673 unique reflections, a = 12.745(3) ?, b = 13.726(3) ?, c = 28.835(6) ?, β = 93.44(3)°, V = 5035.2(17) ?³, Z = 4, space group P2₁/c). In the trimer complex I, the copper atoms are combined by a bridging hydroxy group. The copper atoms are additionally linked pairswise by three tridentate chelating bridging organic anions coordinated to the Cu(II) atoms by the N and O atoms of the deprotonated oxime group and by the N atom of the dihydroisoquinoline moiety. Original Russian Text ? V.I. Sokol, V.V. Davydov, N. Yu. Merkur’eva, E.I. Polyakova, Yu.V. Shklyaev, V.S. Sergienko, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 10, pp. 1643–1652.     

Effects of ionic liquid as additive and the pH of the mobile phase on the retention factors of amino benzoic acids in RP-HPLC

As an organic salt, ionic liquids are widely used as new solvent media. In this paper, three positional isomers, such as o-amino benzoic acid, m-amino benzoic acid, and p-amino benzoic acid are separated with four different ionic liquids as additives to the mobile phase using reversed-phase (RP) high-performance liquid chromatography (HPLC). Amino benzoic acids are biologically active substances; the p-isomer is present in a group of water-soluble vitamins and is widely known as a sunscreen agent. The ionic liquids used are 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium methylsulfate, and 1-octyl-3-methylimidazolium methylsulfate. The effects of the length of the alkyl group on the imidazolium ring and its counterion, the concentrations of the ionic liquid, and the effect of the pH of the mobile phase on the retention factor of the amino benzoic acid isomers are studied. Separation with the ionic liquid in the eluent was better than the separation without the ionic liquid. The pH mainly affected the retention and elution order of the solutes in RP-HPLC.     

Mass transfer effects in preparative chromatography of eremomycin on polymeric sorbents

This work is devoted to the study of the regularities of the sorption of the new antibacterial antibiotic eremomycin on carboxylic sorbents. The main sorption kinetic equilibrium and dynamic parameters for realization of one-act preparative chromatographic process were determined and the difference between gel-like and structurally segregated carboxylic cation exchangers was analyzed. The optimal conditions for sorption and complete desorption of eremomycin were found.