| 1. |
- Eremina, A. V., et al.
(författare)
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Ruthenium(II,III,III) mu(3)-oxotrifluoroacetate with dimethyl sulfoxide : Synthesis, structure, and DTF quantum-chemical calculations
- 2007
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 33:9, s. 669-673
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Tidskriftsartikel (refereegranskat)abstract
- The reaction of [Ru-3(III) (mu(3)-O)(mu-O2CCF3)(6)(H2O)(3)](O2CCF3) in methanol gives two solvates, [Ru3O(O2CCF3)(6)(DMSO)(3)] center dot 1/2H(2)O (I) and [Ru3O(O2CCF3)(6)(DMSO)(3)] center dot H2O (II), of a novel trinuclear mixedvalence Ru(II,III,III) trifluoroacetate complex, where two DMSO molecules are coordinated to the Ru atoms through the O atom, while the third DMSO molecule is coordinated through the S atom. According to the X-ray diffraction data, the complex can crystallize in two crystal systems: triclinic (I) (space group P (1) over bar) and monoclinic (II) (space group P2(1)/m). The unit cell parameters for I are: a = 9.354, b = 11.005, c = 20.846 angstrom, alpha = 99.10, beta = 96.38, gamma = 92.17, Z = 2; R = 7.27%; for I are: a = 9.186, b = 17.044, c = 13.091 angstrom, beta = 101.10, Z = 2; R = 14.18%.
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| 2. |
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| 3. |
- Fischer, A. I., et al.
(författare)
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Synthesis, crystal and molecular structures of the octanuclear cationic mixed-valence cobalt acetate complex
- 2007
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Ingår i: Russian journal of coordination chemistry. - 1070-3284 .- 1608-3318. ; 33:11, s. 789-794
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Tidskriftsartikel (refereegranskat)abstract
- A new octanuclear mixed-valence cobalt acetate complex of the cationic type [Co-4(II) Co4(III) (mu(4)-O)(4)(mu(3)-OMe)(4)(mu-OAc)(6)(H2O)(8)]F-2 center dot 10H(2)O ([I]F-2 center dot 10H(2)O) was prepared by crystallization from a solution of 'cobalt(III) acetate' in a Me2CO-MeOH-H2O-HF mixture and studied by X-ray diffraction. The crystals are monoclinic: space group C2/c, a = 17.222 angstrom, b = 16.836 angstrom, c = 16.586 angstrom, beta = 94.902 degrees, Z = 4, R = 4.37% (I > 2 sigma(I)). In the crystal, the I2+ complex cations, fluoride anions, and solvate water molecules form a three-dimensional (3D) coordination supermolecular system.
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| 4. |
- S A, Simanova, et al.
(författare)
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Adsorption of palladium, platinum, and gold chloride complexes by carbon fibers with various structures
- 2008
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Ingår i: Fibre Chemistry. - : Springer?Business Media, Inc. - 0015-0541 .- 1573-8493. ; 40:4, s. 365-75
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Tidskriftsartikel (refereegranskat)abstract
- Data are given characterizing the effects of the porous structures in activated carbon fibers (ACF) and the amounts of oxidized carbon forms on the extent and rate of adsorption for various chloride complexes of the platinum metals and gold. The adsorption mechanisms on ACF are considered for these metal chloride complexes. The practical significance of the research is considered.
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| 5. |
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| 6. |
- Belyaev, A. N., et al.
(författare)
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Redox properties of rhodium(III) oxo-bridged carboxylate complexes
- 2001
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Ingår i: Russian journal of general chemistry. - 1070-3632 .- 1608-3350. ; 71:8, s. 1186-1193
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Tidskriftsartikel (refereegranskat)abstract
- Chemical and electrochemical oxidation of rhodium (III) oxo-bridged carboxylate complexes was studied. The chemical [with O-3 and Ce(IV) salts] or electrochemical (at potentials of 1.00-1.20 V) oxidations of the binuclear complexes [Rh-2(mu-O)(mu-O2CCH3)(2)(H2O)(6)](2+) and [Rh-2(mu-O)(mu-O2CCF3)(2)(H2O)(6)](2+) leads to the superoxo complexes [Rh-2(mu-O)(O-2(-))(mu-O2CCH3)(2)(H2O)(5)]+ and [Rh-2(mu-O)(O-2(-))(mu-O2CCF3)(2)(H2O)(5)](+) with terminal coordination of O-2(-). The trinuclcar acetate [Rh-3(mu(3)-O)(mu-O2CCH3)(6)(H2O)(3)](+), unlike its trifluoroacetate analog [Rh-3(mu(3)-O)(mu-O2CCF3)(6)(H2O)(3)](+), is oxidized only electrochemically at a potential of 1.38 V. The oxidation of [Rh-3(mu(3)-O)(mu-O2CCH3)(6)(H2O)(3)](+) is reversible and involves formation of an unstable superoxo group O-2(-) between two Rh-3(III)(mu(3)-O) cores.
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| 7. |
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| 8. |
- Simanova, Anna A., 1982-, et al.
(författare)
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Evidence for ligand hydrolysis and Fe(III) reduction in the dissolution of Goethite by desferrioxamine-B
- 2010
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier Ltd. - 0016-7037 .- 1872-9533. ; 74:23, s. 6704-6720
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Tidskriftsartikel (refereegranskat)abstract
- Desferrioxamine-B (DFOB) is a bacterial trihydroxamate siderophore and probably the most studied to date. However, the manner in which DFOB adsorbs at mineral surfaces and promotes dissolution is still under discussion. Here we investigated the adsorption and dissolution reactions in the goethite–DFOB system using both in situ infrared spectroscopic and quantitative analytical methods. Experiments were carried out at a total DFOB concentration of 1 μmol/m2, at pH 6, and in the absence of visible light. Our infrared spectroscopic results indicated that the adsorption of DFOB was nearly complete after a 4-h reaction time. In an attempt to determine the coordination mode at the goethite surface, we compared the spectrum of adsorbed DFOB after a 4-h reaction time to the spectra of model aqueous species. However, this approach proved too simplistic in the case of such a complex ligand as DFOB, and we suggest that a more detailed investigation (IR in D2O, EXAFS of adsorbed model complexes) is needed to elucidate the structure of the adsorbed siderophore. Between a 4-hand 4-day reaction time, we observed the growth of carboxylate stretching bands at 1548 and 1404 cm-1, which are indicators of DFOB hydrolysis. Acetate, a product of DFOB hydrolysis at its terminal hydroxamate group, was quantified by ion chromatography. Its rate of formation was linear and nearly the same as the rate of Fe(III) dissolution. The larger hydrolysis product, a hydroxylamine fragment, was not detected by LC–MS. However, a signal due to the oxidized form of this fragment, a nitroso compound, was found to increase linearly with time, which is an indirect indication for Fe(III) reduction. Based on these findings, we propose that DFOB undergoes metal-enhanced hydrolysis at the mineral surface followed by the reduction of surface Fe(III). While Fe(II) was not detected in solution, this is likely because it remains adsorbed at the goethite surface or becomes buried in the goethite crystal by electron conduction. Taking into account the extent and similarity between the rates of hydrolysis and dissolution, we suggest that a reductive mechanism could play an important part in the dissolution of goethite by DFOB. This possibility has not been considered previously in the absence of light and at circumneutral pH.
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| 9. |
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| 10. |
- Simanova, Anna A., et al.
(författare)
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Formation of ternary metal-oxalate surface complexes on alpha-FeOOH particles
- 2011
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Ingår i: The Journal of Physical Chemistry C. - Washington DC : American Chemical Society. - 1932-7447 .- 1932-7455. ; 115:43, s. 21191-21198
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Tidskriftsartikel (refereegranskat)abstract
- Processes at the aqueous interfaces of metal (hydr)oxide particles greatly influence the mobility, bioavailability, and reactivity of metal ions and ligands. Here we investigated the time-dependent reactions of oxalate or Me(C(2)O(4))(3)(3-) (Me = Fe(III), Al(III), Ga(III), Co(III)) with goethite in aqueous suspension at pH 4 using attenuated total reflectance infrared (ATR-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The data indicate four coordination modes for oxalate and Fe(C(2)O(4))(3)(3-) adsorbed at the goethite surface: (1) outer-spherically with a hydration shell similar to aqueous ligand; (2) outer-spherically but hydrogen bonded to a surface site; (3) inner-spherically to surface iron; (4) inner-spherically within a ternary type A surface complex. In the presence of oxalate, the two outer-sphere complexes form rapidly, but with time these species are partially consumed and the ternary inner-sphere complex is formed as a result of a dissolution-readsorption process. We propose that iron in these ternary complexes is more labile than iron that is mostly embedded in the lattice. Thus, ternary complexation may play an important role in iron bioavailabilty in the environment. For goethite reacted with Al(C(2)O(4))(3)(3-) or Ga(C(2)O(4))(3)(3-), these four surface complexes are accompanied by an additional Al(III) or Ga(III) ternary oxalate surface complex.
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