Synthese,Kristallstruktur und thermischer Abbau von Fluoroaluminaten der Zusammensetzung (NH4)[M(H2O)6][AlF6] (M = Zn,Ni), [Zn(H2O)6][AlF5(H2O)] und (PyH)4[Al2F10] · 4 H2O

Synthesis, Crystal Structure and Thermal Behaviour of Fluoroaluminates of the Composition (NH₄)[M(H₂O)₆](AlF₆) (M = Zn, Ni), [Zn(H₂O)₆][AlF₅(H₂O)], and (PyH)₄[Al₂F₁₀] · 4 H₂O Four new fluoroaluminates were obtained from fluoroacidic solutions of respective metal salts. The compounds of zinc ( I a : P2₁/c, a = 12.688(3), b = 6.554(1), c = 12.697(3) Å, β = 95.21(3)°, V = 1051.5(4) ų, Z = 4) and nickel ( I b : P2₁/c, a = 12.685(3), b = 6.517(1), c = 12.664(2)Å, β = 94.55(2)°, V = 1043.6(4) ų, Z = 4) are isotypic and represent a new structure type consisting of two different cations, NH₄⁺ and [M(H₂O)₆]²⁺ and [AlF₆]^3–‐anions. [Zn(H₂O)₆][AlF₅(H₂O)] ( II : C2/m, a = 10.769(2), b = 13.747(3), c = 6.487(1)Å, β = 100.02(3)°, V = 945.7(3) ų, Z = 4) is characterized by a H₂O/F‐disorder in the [AlF₅(H₂O)]‐octahedra in two trans positions. In (PyH)₄[Al₂F₁₀] · 4 H₂O ( III : Cmc2₁, a = 15.035(3), b = 20.098(4), c = 12.750(4) Å, V = 5364(2) ų, Z = 8), bioctahedral [Al₂F₁₀]^4– anions have been found for the first time. The structures are described and discussed in comparison. The new compounds were used as precursors in order to obtain new AlF₃‐phases. However, the thermal decomposition did not result in the formation of any new metastable AlF₃‐phase. Instead, phase mixtures of either α‐AlF₃ and β‐AlF₃ or AlF₃ and MF₂ were obtained.     

Fluorolytic Sol–Gel Route and Electrochemical Properties of Polyanionic Transition-Metal Phosphate Fluorides

Fluorine-containing polyanionic compounds have attracted much attention in the last few years as potential positive electrode materials for rechargeable batteries. With their formula A_aM_bX_cO₄Y_d (A=Li, Na…; M=Ti, V, Mn, Fe, Co, Ni…; X=P or S, and Y=F, OH, O), they offer a very rich chemistry and their electrochemical properties can be tuned by carefully choosing the different constituting elements. However, synthesis approaches that allow these materials to be obtained at low temperature are almost nonexistent. In this paper, the use of a nonaqueous fluorolytic sol–gel approach is reported to synthesize a tavorite-type LiFePO₄F material and its electrochemical characterization was performed. The obtained material displays an electrochemical performance that positively compares with the literature with an excellent cycling stability (115 mA h⁻¹ g⁻¹ after 100 cycles at C/2 rate). A slight change in the synthesis parameters allowed Li₂CoPO₄F to be successfully obtained, demonstrating the versatility of the reported route, which can be adapted to synthesize other fluorine-containing polyanionic compounds, which are of great interest for energy storage applications.     

Four isomers of c(96) fullerene structurally proven as c(96) cl(22) and c(96) cl(24)

Direct proof of the cage connectivities of four isomers of C(96) , the highest isolable empty fullerene, has been achieved. C(96) fractions, which were isolated from fullerene soot by recycling HPLC, were chlorinated and the resulting single crystals of C(96) Cl(22) and C(96) Cl(24) were studied by X-ray diffraction using synchrotron radiation. D(2) -C(96) (183)Cl(24) (see structure; gray C, green Cl) was obtained in two crystalline modifications.     

The First Experimentally Confirmed Isolated Pentagon Rule (IPR) Isomers of Higher Fullerene C98 Captured as Chlorides,C98(248)Cl22 and C98(116)Cl20

High‐temperature chlorination of pristine C₉₈ fullerene isomers separated by HPLC from the fullerene soot afforded crystals of C₉₈Cl₂₂ and C₉₈Cl₂₀. An X‐ray structure elucidation revealed, respectively, the presence of carbon cages of the most stable C₂‐C₉₈(248) and rather unstable C₁‐C₉₈(116), which represent the first isolated pentagon rule (IPR) isomers of fullerene C₉₈ confirmed experimentally. The chlorination patterns of the chlorides are discussed in terms of the formation of isolated C=C bonds and aromatic substructures on the fullerene cages.     

Local fluorine environments in nanoscopic magnesium hydr(oxide) fluorides studied by F MAS NMR

¹⁹F MAS NMR signals of a variety of X-ray amorphous magnesium hydroxide (oxide) fluorides (MgF_x(OH(R))_2−x (0 < x ≤ 2)) prepared using different synthesis routes are compared and assigned. Relations between their ¹⁹F signal positions and local coordinations are elaborated on the basis of the chemical behaviour and data available for the few crystalline reference compounds known so far. Supported by the superposition model, ¹⁹F signals appearing between −150 ppm and −200 ppm were subdivided into three groups due to local [FMg₆], [FMg₅] and [FMg₄], and [FMg₃] environments, respectively.     

Mobility and reactivity of lattice oxygen in Gd-doped ceria promoted by Pt

Summary For samples of the Ce_1-xGd_xO_2-y system prepared by the Pechini route and promoted with Pt, the mobility and reactivity of lattice oxygen were found to correlate with the density of surface and bulk anion vacancies.     

Hydrodechlorination of CF3-CCl2f (CFC-114a) on Pd/b-AIF3

The formation of CF₃-CH₂F (HFC-134a) by catalytic hydrodechlorination of CF₃-CCl₂F (CFC-114a) has been studied utilizing the recent PulseTA® technique. Instead of hydrogen as reactant, deuterium was used which facilitates the detection of the reaction products, i.e. the discrimination of various hydrofluorocarbons (HFC), by mass spectrometry. The product composition confirms a reaction mechanism via the carbene CF₃-CF. Water traces which are retained in the channel structure of the catalyst interact with chemisorbed deuterium thus explaining the formation of hydrogenated fluorocarbons as well. The obtained results demonstrate the potential of the pulse technique for the investigation of solid state reactions.