Über die Deammonisierung und Dehydroxylierung von NH4-Chabasit

Deammoniation and Dehydrosylation of NH₄-Chabazite The deammoniation of NH₄-chabazite is completely reversible. Compared to other investigated zeolites the hydrogen form of chabazite remains stable at higher temperatures and over a wider temperature range. Thermoanalytic and by IR spectrophotometry two types of OH groups with OH-stretching bands at 3565 and 3615 cm^?1 can be distinguished. Water saturation of H-chabazite at room temperature results in irreversible changes of the crystal structure. The thermostability of the deriving lattice is extremely low and no acidic OH groups are detectable any more. It is supposed that in the completely hydrated H-chabazite acidic H₃O⁺ ions solved out aluminium from the lattice which occupies some of the cationic lattice sites. The dehydroxylation is an irreversible process and is accompanied by a lattice collapse.     

Oxydative Derivatisierung von 1,3,2-Dioxaphosphorinanen unter Verwendung von Tetrachlormethan als Oxydans

Oxidative Derivatization of 1,3,2-Dioxaphosphorinanes Using Carbon Tetrachloride as Oxidant 2-Alkoxy- and 2-dialkylamido-1,3,2-dioxaphosphorinanes react with CCl₄ in presence or absence of protic nucleophiles under ring opening forming acyclic derivatives of phosphates. 2-Anilido-1,3,2-dioxaphosphorinane, however, forms 2-amido-2-phenylimido-1,3,2-dioxaphosphorinanes ( 6 ) retaining the heterocyclic ring system. The latter are also obtained in the reaction of 2-dialkylamido-1,3,2-dioxaphosphorinanes with CCl₄ and aniline. 2-Amino-2-oxo-1,3,2-dioxaphosphorinanes ( 8 ) are prepared from 2-hydrido-2-oxo-1,3,2-dioxaphosphorinane ( 7 ) by means of the Atherton-Todd reaction. In combination with the Staudinger reaction the latter yields N(2-oxo-1,3,2-dioxaphosphorinanyl)phosphazenes ( 10 ).     

Einkristalle von (NH4)ZrF5 und (NH4)HfF5 durch Oxidation von Zirconium und Hafnium mit (NH4)HF2

Synthesis and Crystal Structure of (NH₄)ZrF₅ and (NH₄)HfF₅ by Oxidation of Zirconium and Hafnium with (NH₄)HF₂ Colourless single crystals of NH₄ZrF₅ ( 1 ) and NH₄HfF₅ ( 2 ) are obtained by reaction of the respective metal powders with NH₄HF₂ (4 weeks) in sealed Monel metal containers at 450 °C. They crystallize with the monoclinic space group P2₁/c with ( 1 / 2 ) a = 778.16(14)/786.35(12), b = 790.75(9)/786.64(8), c = 792.44(12)/786.01(12), β = 119.177(12)/119.828(10) isotypic to TlZrF₅.     

Die Ammonolyse von (NH4)2GeF6. Darstellung und Struktur von NH4[Ge(NH3)F5]

Ammonolysis Reaction of (NH₄)₂GeF₆. Synthesis and Structure of NH₄[Ge(NH₃)F₅] (NH₄)₂GeF₆ reacts with ammonia to yield NH₄[Ge(NH₃)F₅] at 280°C. The reaction path was elucidated by in situ time and temperature resolved X-ray powder diffraction. NH₄[Ge(NH₃)F₅] crystallizes isostructurally to NH₄[Si(NH₃)F₅] in the tetragonal space group P4/n (No. 85) with lattice constants a = 619.41(1) pm and c = 724.70(1) pm. The germanium atom is coordinated by five fluorine atoms and the nitrogen atom of the ammonia molecule. The ammonium cation is located on the Wyckoff position (2 a) in P4/n. The crystal structure is stabilized by extensive hydrogen bonding.     

Kristallstrukturanalyse von (NH4)2NaInF6

Single Crystal Structure of (NH₄)₂NaInF₆ (NH₄)₂NaInF₆ has been synthesized via a novel route from In₂O₃, NaF and NH₄F and its crystal structure has been determined using single crystal techniques (Fm3 m, a = 8.6675(3) Å, Z = 4, 4 106 reflections, R = 0.007). The crystal structure derives from the elpasolite type of structure, the ammonium ions are not disordered.     

Untersuchungen zur heterogen-katalysierten Ringalkylierung von Toluen mit Methanol an modifizierten ZSM-5-Zeolithen

Studies of the Heterogeneous Catalytical Ring Alkylation of Toluene with Methanol on Modified Zeolites ZSM-5 Various ways for controlling the catalytic activity, the shape selectivity, and the deactivation behaviour of modified zeolites ZSM-5 has been shown by the example of the heterogeneous catalytical conversion of toluene with methanol. The preferred formation of the industrially interesting para-xylene is possible by use of ZSM-5-zeolites composed of large crystals, by dealumination of the external surface after hydrothermal treatment, by poisoning of external active centres after impregnation with inorganic salts as well as by isomorphic incorporation of boron for silicon and/or aluminium in the zeolite framework.     

Reindarstellung und Kristallstruktur von Lithiumnitridhydrid,Li4NH,Li4ND

Preparation and Crystal Structure of Lithium Nitride Hydride, Li₄NH, Li₄ND Single phase Li₄NH was prepared by the reaction of Li₃N and LiH at 490°C. Its structure has been solved from x-ray and time-of-flight neutron powder diffraction data. Li₄NH crystallizes in an ordered variant of the Li₂O structure. N and H occupy the sites of two interpenetrating “extended” diamond lattices. Li occupies all N₂H₂ tetrahedral voids and is found to be shifted into a N₂H tetrahedral face. As a result H is in compressed tetrahedral coordination by Li, while N is in bisdisphenoidal coordination by Li. Alternatively, the Li₄NH structure may be regarded as a [Li₄N]⁺threedimensional net, its voids being filled up with H^?. Li₄NH is a reactive solid, which decomposes to imide when in contact with N₂ or H₂ at some 400°C.     

Beiträge zum thermischen Verhalten von Sulfaten. VIII. Zum chemischen Transport von FeSO4 mit NH4Cl und von von Fe2(SO4)3 mit Cl2 oder NH4Cl. Experimente und Modellrechnungen

Contributions on the Thermal Behaviour of Sulfates. VIII. The Chemical Vapour Transport of FeSO₄ with NH₄Cl and Fe₂(SO₄)₃ with Cl₂ or NH₄Cl. Experiments and Calculations Well shaped crystals of FeSO₄ and Fe₂(SO₄)₃ can be grown by CVT (T₁? 650°C). We investigated the dependence of the transport rate on the concentration of the transport agent (Fe₂(SO₄)₃/Cl₂ and Fe₂(SO₄)₃/NH₄Cl) as well as on the temperature (FeSO₄/NH₄Cl and Fe₂(SO₄)₃/Cl₂). Using Δ_fH(FeSO₄) = ?220 kcal/ mol, C^p(T) = 30.1 + 9.9 · 10^?3 ×T and Δ_fH(Fe₂(SO₄)₃) = ?615.4 kcal/mol a satisfying agreement between thermodynamical calculations and experimental results can be reached     

Synthese und Kristallstruktur zweier Formen von Ammoniummonomolybdat (NH4)2MoO4

Synthesis and Structure of Two Forms of Ammonium Monomolybdate (NH₄)₂MoO₄ Ammonium monomolybdate (NH₄)₂MoO₄ exists in two different polymorphic forms which differ in their lattice constants and in the arrangement of the ammonium cations relative to the molybdate anions. The ammonium molybdates (NH₄)₂MoO₄(mS60)¹⁾ and (NH₄)₂MoO₄(mP60)²⁾ are synthesized by the reaction of ammonia and (NH₄)₆[Mo₇O₂₄] · 4 H₂O. (NH₄)₂MoO₄(mS60) crystallizes isostructural to the potassium compound in space group C2/m (Nr. 12) and lattice constants a = 1263.6(3), b = 652.2(1) pm, c = 776.4(2) pm and β = 117.36(1)° (V = 568.3(2) · 10⁶ pm³) containig four formula units per unit cell (R = 0.0250). (NH₄)₂MoO₄(mP60) crystallizes monoclinic in space group P2₁/n (Nr. 14) and lattice constants a = 622.8(2), b = 777.0(1) pm, c = 1118.8(4) pm and β = 98.09(2)° (V = 536.0(3) · 10⁶ pm³) (R = 0.0205). The different arrangements of the polyhedra within the unit cell is caused by hydrogen bridges. A transition point was not yet determined.     

Synthese und Kristallstrukturen von NH4[Si(NH3)F5] und [Si(NH3)2F4]

Synthesis and Crystal Structures of NH₄[Si(NH₃)F₅] and [Si(NH₃)₂F₄] Single crystals of NH₄[Si(NH₃)F₅] and [Si(NH₃)₂F₄] are obtained by reaction of silicon powder with NH₄HF₂ in sealed Monel ampoules at 400°C. NH₄[Si(NH₃)F₅] crystallizes with the tetragonal space group P4/n (no. 85) with a = 614.91(7) pm, c = 721.01(8) pm, Z = 2. Characteristic for the structure is the anionic octahedron [Si(NH₃)F₅]^?. Si(NH₃)₂F₄ crystallizes with the monoclinic space group P2₁/c (no. 14) with a = 506.9(1) pm, b = 728.0(1) pm, c = 675.9(1), β = 93,21(2)°, Z = 2. Trans-[Si(NH₃)₂F₄] molecules are characteristic for this structure.     

Die IR-Spektren von NH4UO2AsO4·3H2O und NH4UO2PO4·3H2O

The infrared spectra of the title compounds, as well as that of the structurally related mineral meta-autunite, [Ca(UO₂)₂(PO₄)₂·n H₂O], are reported and discussed using the available crystallographic data. The results can be considered as representative for the full group of the so-called torbernite-minerals.     

Untersuchungen an oxidischen Katalysatoren. XLV. Umwandlung von Aromaten an dealuminierten ZSM-5-Zeolithen

Studies on Oxide Catalysts. XLV. Conversion of Aromatics on Dealuminated Zeolites ZSM-5 The catalytic properties of zeolites ZSM-5 dealuminated by hydrochloric acid are investigated in the isomerization of m-Xylene, the disproportionation of toluene and in the alkylation of toluene with methanol. Besides the increase of the Si/Al ratio, the dealumination leads to an inversion of the Si/Al concentration gradient in crystallites, to a shift of acidity spectrum and consequently to a change in catalytic activity and selectivity.     

Kristallstruktur von (NH4)3SnF7: Ein Doppelsalz gemäß (NH4)3[SnF6]F und kein (NH4)4SnF8

Crystal Structure of (NH₄)₃SnF₇: A Double Salt According to (NH₄)₃[SnF₆]F and not (NH₄)₄SnF₈ (NH₄)₃SnF₇ is obtained as colourless single crystals from the reaction of NH₄HF₂ with tin powder at 300°C. The crystal structure (cubic, Pm3m, Z = 1, a = 602.5(1) pm at 293 K; a = 598.0(1) pm at 100 K) contains [SnF₆]^2? octahedra and lonesome F^? ions surrounded by NH₄⁺ cations only; it may be considered as a derivative of the Cu₃Au-type of structure according to Cu₃[Au]□ ?(NH₄)₃[SnF₆]F. The F^? ions of the [SnF₆]^2? octahedra with their Sn⁴⁺ centre in the origin of the unit cell at m3m are disordered in different ways at 293 and 100 K, respectively.