The synthesis and selected properties of Co<Subscript>2</Subscript>InV<Subscript>3</Subscript>O<Subscript>11</Subscript>

It has been demonstrated that Co₂V₂O₇ and InVO₄ react with each other forming a new compound of the Co₂InV₃O₁₁ formula, when their molar ratio is equal to 1:1, or among CoCO₃, In₂O₃ and V₂O₅, mixed at a molar ratio of 4:1:3. This compound melts incongruently at the temperature of 960±5°C, depositing crystals of InVO₄. It crystallizes in the triclinic system and the unit cell parameters amount to: a=0.6524(6) nm, b=0.6885(5) nm, c=1.0290(4) nm, α=96.5°, β=104.1°, γ=100.9°, Z=2. The phase equilibria being established in the Co₂V₂O₇–InVO₄ system over the whole components concentration range up to the solidus line were described.     

New Supramolecular Complex Assembled through Hydrogen Bonds. Crystal Structure of Co(PMBP-tsc)_2 ·2DMF·2H_2O

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Synthese und Kristallstruktur von Ba4,5Ca1,5La2Fe4O15, Ba5CaEu2Fe4O15 und Ba5CaNd2Co4O15

Synthesis and Crystal Structure of Ba_4.5Ca_1.5La₂Fe₄O₁₅, Ba₅CaEu₂Fe₄O₁₅ and Ba₅CaNd₂Co₄O₁₅ The compounds (I) Ba_4.5Ca_1.5La₂Fe₄O₁₅, (II) Ba₅CaEu₂Fe₄O₁₅ and (III) Ba₅CaNd₂Co₄O₁₅ were prepared and investigated by single crystal X-Ray technique. They belong to the Ba₆Nd₂Al₄O₁₅ typ, space group C? P6₃mc, (I): a = 11.677, c = 6.959 Å; (II): a = 11.570, c = 6.892 Å; (III): a = 11.604, c = 6.839 Å, Z = 2. The crystal chemistry of these substances will be discussed.     

Darstellung und Kristallstruktur von Cobalt(II)-Hexaoxodiphosphat(P?P)(4−)-dodecahydrat,Co2P2O6 · 12 H2O

Synthesis and Crystal Structure of Cobalt(II)-hexaoxodiphosphate(P? P)(4?)-dodecahydrate, Co₂P₂O₆ · 12 H₂O Co₂P₂O₆ · 12H₂O was obtained by cleavage and simultaneous oxidation of cyclo-hexaphosphate(III) in a solution of ethanol and aqueous ammonia. The crystal structure has been determined (1 898 independent diffractometer data): space group Pbam (No. 55), a = 6.710(2), b = 12.196(2), c = 10.073(3) Å, V = 825.3(1) ų, Z = 2, R = 0.060. The P₂O₆^4? anions show site symmetry C_2h and are connected to form chains via cobalt. Two cobalt ions together with two sets of four water molecules and two oxygen atoms of P₂O₆^4? form pairs of edge connected octahedra. The common edges are formed by the oxygen atoms of the P₂O₆ groups.     

The homogeneity range of lyonsite-type phase existing in the CrVO4 - Co3V2O8 system

In the work presented here, the way of obtaining the phase with general formula Co_3+1.5xCr_2–x(VO₄)₄ (0 ≤ × < 0.4) is demonstrated. A new phase is detected in CrVO₄ - Co₃V₂O₈ that is formed in one of the intersection of the ternary CoO - V₂O₅ - Cr₂O₃ system. Monophasic Co₃Cr₂(VO₄)₄ (Co_3+1.5xCr_2−x(VO₄)₄, where × = 0) was obtained from both a mixture comprising CrVO₄ and Co₃V₂O₈ as well as from the mixture of CoV₂O₆ with CoCr₂O₄. The Co_3+1.5xCr_2−x(VO₄)₄ is isotypic with the those demonstrating the lyonsite-type structure. The temperature of melting for the new compound was established using the DTA methods.      

A quarter of a century after its synthesis and with >200 papers based on its use, `Co(CO3)0.5(OH)·0.11H2O′ proves to be Co6(CO3)2(OH)8·H2O from synchrotron powder diffraction data

The successful attempt to solve the crystal structure of Co(CO₃)_0.5(OH)·0.11H₂O (denoted CCH ), based on synchrotron powder diffraction data, leads to a drastic revision of the chemical formula to Co₆(CO₃)₂(OH)₈·H₂O [hexacobalt(II) bis(carbonate) octahydroxide monohydrate] and to a hexagonal cell instead of the orthorhombic cell suggested previously [Porta et al. (1992). J. Chem. Soc. Faraday Trans. 88 , 311–319]. This results in a new structure‐type related to malachite involving infinite chains of [CoO₆] octahedra sharing edges along a short c axis, delimiting tunnels having a three‐branched star section. All reports discussing cobalt hydroxycarbonates ( CCH ) without any structural knowledge and especially its topotactic decomposition into Co₃O₄ have, as a result, to be reconsidered.     

Phase Relations in The Subsolidus Area of The CoV2O6–CoMoO4–CoO Subsystem Included by The Ternary CoO–V2O5–MoO3 System

The phase diagram of CoV₂O₆–CoMoO₄–CoO system in subsolidus area was investigated by DTA and XRD methods. It was shown that this area consisted of five subsidiary systems in which there existed three solid phases. The melting temperatures of these systems were also determined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Aqueous/organic biphasic hydroformylation of 1‐octene catalyzed by Co2(CO)8/Ph2P(CH2CH2O)nMe

The aqueous/organic biphasic hydroformylation of 1‐octene catalyzed by Co₂(CO)₈/Ph₂P(CH₂CH₂O)_nMe, an in situ formed thermoregulated phase‐transfer cobalt catalyst, has been developed. The catalyst activity in this biphasic system was as high as that in the homogeneous system. The yield of oxo‐products was 93% when the reaction was carried out at 180 °C and under 4.0 MPa syngas pressure for 20 h. The catalyst could be easily recovered in the aqueous phase by decanting after the reaction system was cooled, and reused in consecutive reaction without any treatment. The loss of Co in the organic phase was less than 1% on average of five successive runs. Copyright © 2012 John Wiley & Sons, Ltd.     

Enhanced third‐order nonlinear optical properties determined in thin films using the Z‐scan technique: bis(μ‐4,4′‐oxydibenzoato)bis[(4′‐phenyl‐2,2′:6′,2′′‐terpyridine)cobalt(II)]

π‐Conjugated organic materials exhibit high and tunable nonlinear optical (NLO) properties, and fast response times. 4′‐Phenyl‐2,2′:6′,2′′‐terpyridine (PTP) is an important N‐heterocyclic ligand involving π‐conjugated systems, however, studies concerning the third‐order NLO properties of terpyridine transition metal complexes are limited. The title binuclear terpyridine Co^II complex, bis(μ‐4,4′‐oxydibenzoato)‐κ³O,O′:O′′;κ³O′′:O,O′‐bis[(4′‐phenyl‐2,2′:6′,2′′‐terpyridine‐κ³N,N′,N′′)cobalt(II)], [Co₂(C₁₄H₈O₅)₂(C₂₁H₁₅N₃)₂], (1), has been synthesized under hydrothermal conditions. In the crystal structure, each Co^II cation is surrounded by three N atoms of a PTP ligand and three O atoms, two from a bidentate and one from a symmetry‐related monodentate 4,4′‐oxydibenzoate (ODA²⁻) ligand, completing a distorted octahedral coordination geometry. Neighbouring [Co(PTP)]²⁺ units are bridged by ODA²⁻ ligands to form a ring‐like structure. The third‐order nonlinear optical (NLO) properties of (1) and PTP were determined in thin films using the Z‐scan technique. The title compound shows a strong third‐order NLO saturable absorption (SA), while PTP exhibits a third‐order NLO reverse saturable absorption (RSA). The absorptive coefficient β of (1) is −37.3 × 10⁻⁷ m W⁻¹, which is larger than that (8.96 × 10⁻⁷ m W⁻¹) of PTP. The third‐order NLO susceptibility χ⁽³⁾ values are calculated as 6.01 × 10⁻⁸ e.s.u. for (1) and 1.44 × 10⁻⁸ e.s.u. for PTP.     

Herstellung keramischer Pulver. IX. Zur Bildung von NiMn2 O4 und ZnMn2O4 durch Zersetzung von [Ni(H2O)6] (MnO4)2 und [Zn(H2O)6] (MnO4)2

Preparation of Ceramic Powders. IX. NiMn₂O₄ and ZnMn₂O₄ Formation by Decomposition of [Ni(H₂O)₆] (MnO₄)₂ and [Zn(H₂O)₆] (MnO₄)₂ Improved preparation of Ba(MnO₄)₂ from BaMnO₄ is reported. Thermal or hydrothermal decomposition of [Ni(H₂O)₆] (MnO₄)₂ yields intermediately an amorphous manganate(IV) which forms crystalline NiMnO₃ and α-Mn₂O₃ in the range T > 400°C. NiMn₂O₄ is formed above 730°C in accordance with the phase diagram. On the other hand, ZnMn₂O₄ is already at 300°C obtained from [Zn(H₂O)₆](MnO₄)₂ at hydrothermal conditions.     

Phase Equilibria in the V2O5-Sb2O4 System

Differential thermal analysis (DTA) and X-ray powder diffraction (XRD) were used to study phase equilibria, established in air in the V₂O₅-Sb₂O₄ system up to 1000°C. It has been found that there is a new phase =SbVO₅. The =SbVO₅ has been prepared by two methods: by heating equimolar mixtures of V₂O₅ and α-Sb₂O₄ in air and by oxidation of the known phase of rutile type obtained in pure argon at temperatures between 550 and 650°C. Thermal decomposition of =SbVO₅ in the solid state starts at 710°C giving off oxygen. The results provide a basis for constructing only a part of the phase diagram of the investigated system (up to 50.00 mol% Sb₂O₄). This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal behaviour,surface properties and vibrational spectroscopic studies of the synthesized Co3xNi3−3x(PO4)2·8H2O (0 ≤ x ≤ 1)

Co_3xNi_3−3x(PO₄)₂·8H₂O (x = 1, 0.8, 0.6, 0.4, 0.2, and 0) were synthesized via simple wet chemical reaction and energy saving route method. The final decomposition products of hydrates are corresponding anhydrous tri(cobalt nickel) diphosphates. The metal and water contents of the synthesized hydrates were confirmed by AAS and TG/DTG/DTA techniques, respectively. The observed metal and water contents agree well with the formula of the title compounds. The crystal structures and lattice parameters as well as crystallite sizes of the studied compounds were determined using XRD data. The results from XRD and TG/DTG/DTA techniques confirmed that Co_3xNi_3−3x(PO₄)₂·8H₂O at all ratios were the single phase. The FTIR spectra of studied compounds were recorded and assigned. The thermal behaviours of single and binary tri(cobalt nickel) diphosphate octahydrates were studied for the first time. The morphologies of the studied compounds were investigated by using the SEM technique. The micrographs of all studied compounds exhibited the thin plated morphology. The surface area and the pore size data of anhydrous forms were measured by N₂ adsorption at −190 °C according to the BET method. The anhydrous forms of binary metal phosphate at x = 0.8, Co_2.4Ni_0.6(PO₄)₂, exhibits the highest surface area and expects to improve the catalytic activity.     

Ein neuartiges Polyoxocobaltat(II)‐Anion in Rb2Co2O3

A New Polyoxocobaltate(II) Anion in Rb₂Co₂O₃ Rb₂Co₂O₃ was prepared via the azide/nitrate route. Mixtures of the precursors Co₃O₄, RbN₃ and RbNO₃ in the molar ratios 6:17:1 were heated in a special regime up to 450 °C and annealed at this temperature for 50 h in silver crucibles. Single crystals have been grown by subsequent annealing of prepared powder at 450 °C for 500 h in silver crucibles, which were sealed in glass ampoules under dried Ar. According to the X‐ray analysis of the crystal structure (Pnma, Z = 8, 11.729(2), 6.058 (1), 8.004(1) Å) cobalt is trigonal planar coordinated by oxygen atoms. The CoO₃‐units share through all corners and build up an infinite two‐dimensional Co₂O₃‐network.     

Magnetically separable CoFe2O4/CoxFey/activated carbon composites for Cd(II) removal from wastewater

CoFe₂O₄ and Co_x Fe_y were anchored into activated carbon (AC) to synthesize CoFe₂O₄/Co_x Fe_y /AC composites using the sol–gel method for Cd(II) adsorption from wastewater. The results indicated that CoFe₂O₄ and Co_x Fe_y nanoparticles existed in the pores of AC. The magnetic properties of CoFe₂O₄/Co_x Fe_y /AC indicated it could be separated and retrieved easily using an external magnet after Cd(II) adsorption. The effects of solution pH, temperature and initial Cd(II) concentration on the Cd(II) adsorption of AC and CoFe₂O₄/Co_x Fe_y /AC were investigated. The standard free energy, enthalpy change and entropy change were evaluated. The kinetic parameters of Langmuir and Freundlich isothermal equation were analyzed, and the Freundlich kinetic model was feasible for describing the Cd(II) adsorption process of CoFe₂O₄/Co_x Fe_y /AC composites.     

Syntheses,Characterization and Equilibrium between Mono—and Aqua—bridged Dicobalt（Ⅱ）Complexes.A Structural Model for Methionine Aminopeptidase

A monomeric complex [Co(Im)₂(O₂CMe)2] (1) and a novel aquabridged dimeric complex [Co₂(μ‐H₂O)(μ‐CMe)₂(Im)₄‐(O₂CMe)₂] (2) (Im = imidazole) have been synthesized and characterized. Complexes 1 and 2 coexisted in solution. Pure forms of either complex can be obtained from the same solution by controlling the crystallization conditions. All two complexes possess a carboxylate‐Im‐cobalt(II) triad system analogous to the carboxylate‐histidine‐metal triad systems that have been found in many zinc enzymes and cobalt(II)‐substituted enzymes. In 2, two Co²⁺ ions are connected by a water molecule in a bridging fashion with Co°Co [0.3687(1) nm], Co—OH₂ [0.2159(3) nm], and Co‐OH₂‐Co [117.2(3)°], in which the water molecule is further stabilized by two intramolecular hydrogen bonds with the oxygens of the terminal monodentate acetate groups with the distance of O…0 [0.2609(7) nm]. The terminal monodentate acetate groups display quite abnormal geometry due to the strong “pulling effect” on the carboxylates by intermolecular and intramolecular hydrogen bonds. Complex 2 showed weak antiferromagnetic coupling at low temperature with g = 2.22 and J = ?1.60 cm^?1.     

Heterometallic mixed-valence complex with a {CoIICoIIICu2O4} core as a new type of cobalt-based oxide cubane

A tetranuclear heterometallic complex formulated as [Co₂Cu₂(L)₃(ea)(H₂O)(NCS)₂], where H₂L = 2-((2-hydroxyethyl)iminomethyl)-phenol and Hea = 2-aminoethanol, has been obtained by self-assembly and characterized by single crystal X-ray diffraction. The crystal structure of the complex represents a new {Co^IICo^IIIM₂} type of cobalt-based oxide cubane complex according to the classification which has been made via CSD structural analysis.     

Thermal Analysis of Cobalt(II) Salts with some Carboxylic Acids

The thermal analysis of CoC₂O₄·2H₂O, Co(HCOO)₂·2H₂O and Co(CH₃COO)₂·4H₂O was carried out with simultaneous TG-DTG-DTA measurements under non-isothermal conditions in air and argon atmospheres. The intermediates and the end products of decomposition were characterised by X-ray diffraction and IR and UV-VIS spectroscopy. The decomposition of the studied compounds occur in several stages. The first stage of dissociation of each compound is dehydration both in air and argon. The next stages differ in air and argon. The final product of the decomposition of each compound in air is Co₃O₄. In argon it is a mixture of Co and CoO for cobalt(II) oxalate and cobalt(II) formate but CoO for cobalt(II) acetate. This revised version was published online in August 2006 with corrections to the Cover Date.     

A novel two‐dimensional cobalt(II) complex composed of one‐dimensional twisted pair‐like chains: poly[[tetraaquabis(μ3‐pyridine‐2,5‐dicarboxylato‐κ4N,O2:O5:O5′)dicobalt(II)] dihydrate]

A novel neutral polymer, {[Co₂(C₇H₃NO₄)₂(H₂O)₄]·2H₂O}_n, was hydrothermally synthesized using pyridine‐2,5‐dicarboxylate (2,5‐PDC²⁻) as the organic linker. It features a two‐dimensional layer structure constructed from one‐dimensional {[Co(2,5‐PDC)₂]²⁻}_n chains interlinked by [Co(H₂O)₄]⁺ units. The two Co^II cations occupy special positions, sitting on inversion centres. Each 2,5‐PDC²⁻ anion chelates to one Co^II cation via the pyridine N atom and an O atom of the adjacent carboxylate group, and links to two other Co^II cations in a bridging mode via the O atoms of the other carboxylate group. In this way, the 2,5‐PDC²⁻ ligand connects three neighbouring Co^II centres to form a two‐dimensional network. The two‐dimensional undulating layers are linked by extensive hydrogen bonds to form a three‐dimensional supramolecular structure, with the uncoordinated solvent molecules occupying the interlamellar region.     

A Novel Adipate Bridged Supramolecular Layer: Crystal Structure of the Cobalt(II) Complex [(μ‐C6H8O4)4/2Co(μ‐H2O)2Co(H2O)4] · 4 H2O

The pale‐rose compound [(μ‐C₆H₈O₄)_4/2Co(μ‐H₂O)₂Co(H₂O)₄] · 4 H₂O was prepared from adipic acid and CoCO₃ in aqueous solution. The crystal structure (monoclinic, P2₁/n (no. 14), a = 8.061(1), b = 15.160(2), c = 9.708(2) Å, β = 90.939(7)°, Z = 2, R = 0.0405, wR² = 0.0971) consists of adipate bridged supramolecular [(μ‐C₆H₈O₄)_4/2Co(μ‐H₂O)₂Co(H₂O)₄] layers and hydrogen bonded H₂O molecules. The cobalt atoms Co1 and Co2 are distorted octahedrally coordinated by the O atoms of two bridging trans‐H₂O molecules and four bidentate adipate anions (Co1) and by the O atoms of two bridging trans‐H₂O molecules and four monodentate H₂O molecules (Co2), respectively. Equatorial bonds: d(Co1–O) = 2.048 Å (2 × ), 2.060 Å (2 × ); d(Co2–O) = 2.057 Å (2 × ), 2.072 Å (2 × ). Axial bonds: d(Co1–O) = 2.235 Å (2 × ); d(Co2–O) = 2.156 Å (2 × ).     

Studies of Nano－sized Co304 as Anode Materials for Lithium－ion Batteries

The structural evolution of the Co₃O₄ fine powders prepared by rheological phase reaction and pyrolysis method upon different temperature has been investigated using X‐ray diffraction (XRD) topography. The electrochemical performance of Co₃O₄ electrode materials for Li‐ion batteries is studied in the form of Li/Co₃O₄ cells. The reversible capacity as high as 930 mAh/g for the Co₃O₄ sample heat‐treated at 600 °C is achieved and sustained over 30 times charge‐discharge cycles at room temperature. The detailed information concerning the reaction mechanism of Co₃O₄ active material together with lithium ion is obtained through ex‐situ XRD topography, X‐ray photoelectron spectroscopy (XPS) analysis and cyclic voltammetry (CV) technique. And it is revealed that a “two‐step” reaction is involved in the charge and discharge of the Li/Co₃O₄ cells, in which Co₃O₄ active material is reversibly reduced into xCoO(3 ‐ x)CoO and then into metallic Co.