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89 articles match your search "mixed-valent"Results 1 to 10, sorted by relevance:
research communications
The title compound represents a ionic mixed-valent tin(II)–tin(IV) compound with the bivalent tin atom as central atom of the cation and the tetravalent tin atom as central atom of the anion. Regarding the first and second coordination sphere, the bivalent tin atom is fourfold, seesaw and fivefold, trapezoid–pyramidal coordinated while the tetravalent tin atom exhibits an octahedral coordination.
research papers
The Fe2+ to Fe3+ oxidation in oxoborates vonsenite and hulsite leads to a decrease of values of unit-cell volumes, volumetric thermal expansion coefficients and subsequent solid-phase decomposition. A partial magnetic ordering in hulsite is observed for the first time with Tc ∼383 K, which is accompanied with unusual changes of thermal expansion coefficients.
research communications
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K0.7[FeII3.7FeIII1.3(HPO3)6]·5H2O was synthesized under mild hydrothermal conditions. The open-framework phosphite contains channels extending along [001] in which disordered potassium cations and water molecules are located.
polyoxometalates
The mixed-valent 10-managanese-containing 36-tungsto-4-arsenate(V) [MnIII6MnIV4O4(OH)12(H2O)12(A-β-AsW9O34)4]22− was synthesized in a one-pot reaction in aqueous medium and characterized as a mixed potassium–sodium salt in the solid state by FT–IR spectroscopy and single-crystal XRD, as well as elemental and thermogravimetric analyses.
inorganic compounds
Dilanthanum triniobium disulfide octaoxide, La2Nb3S2O8, crystallizes in the orthorhombic space group Pnnm and is isostructural with the Ln2Ta3X2O8 (Ln = La, Ce, Pr and Nd, and X = S and Se) family of tantalum compounds.
data reports
The title compound features a dinuclear chloride-bridged palladium complex bearing two equivalents of the novel monoanionic mixed valent (λ3-P)—N—(λ5-P) ligand.
data reports
The crystal structure of (NH4)2V3O8 has been redetermined using data collected at 0.61 Å resolution, showing that the ammonium cation is disordered by rotation around a non-crystallographic axis.
research communicationsOpen access
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I—PtIV—IPtII chains are observed in the mixed-valent title salt. Extensive hydrogen bonding involving the amino groups, hydrogen sulfate counter-anions and water molecules of crystallization stabilizes the crystal packing.
I—PtIV—IPtII chains are observed in the mixed-valent title salt. Extensive hydrogen bonding involving the amino groups, hydrogen sulfate counter-anions and water molecules of crystallization stabilizes the crystal packing.inorganic compoundsOpen access
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The mixed-valent titanium phosphate, Li2Ti2(PO4)3, has been prepared by the reactive halide flux method. The title compound is isostructural with Li2TiM(PO4)3 (M = Fe, Cr) and Li2FeZr(PO4)3 and has the same 3∞[Ti2(PO4)3]2− framework as the previously reported Li3-xM2(PO4)3 phases. The framework is built up from corner-sharing TiO6 octahedra and PO4 tetrahedra, one of which has 2 symmetry. The Li+ ions are located on one crystallographic position and reside in the vacancies of the framework. They are surrounded by four O atoms in a distorted tetrahedral coordination. The classical charge-balance of the title compound can be represented as Li+2(Ti3+/Ti4+)(PO43−)3.
abstracts
The first λ3,λ5-tetraphosphete contains a 4π-electron four-membered ring as the central structural unit of a dispirocyclic system and can thus be classified as an analogue to diphosphetes and cyclodiphosphazenes. According to its crystal structure the central P4 unit exhibits not only P–P bonds which are of equal length (P1–P2 2,139(1) Å, P1–P2A 2,142(1) Å), but also rhombic distortion (P1–P2–P1A 79,4(1)0, P2–P1–P2A 100,6(1)0).[1] Therefore its electronic structure cannot be described as 'Phosphacyclobutadiene' but either as a bis(ylide) or as a system with delocalized double bonds. After various quantum chemical calculations and an extensive examination of its reaction and coordination behavior failed to answer this question, we addressed the problem via a detailed analysis of its charge density distribution. The experimental charge density based on high resolution X-ray diffraction data collected at low temperature is determined by multipole least squares refinement using the program package XD2006.[2] In a first step, the static deformation density exhibits charge density which is located mainly outside of the P4 ring plane at the λ3-phosphorus atoms but simultaneously redistributed into the P–P bond area. In addition to that, a study of its topological properties and an inspection of the Laplacian of the electron density according to Bader's `Quantum Theory of Atoms in Molecules' (QTAIM)[3] further highlight the bonding features. They reveal polar Si–N, Si–C and P–N bonds with a decreasing amount of electrostatic contribution as well as four valence shell charge concentrations (thus sp3 hybridization) at each of the phosphorus atoms. Finally supported by theoretical calculations, the results illustrate the unique bonding situation in the P4 unit combining a high ylidic character with unusual not exclusively sigma-like P–P bonds.
