Zur kenntnis ‚Kationen-reicher’︁ Tantalate und Niobate Über Na5TaO5 und Na5NbO5

On Tantalates and Niobates ‘rich in Cations’. On Na₅TaO₅ and Na₅NbO₅ Colourless, transparent single crystals of Na₅TaO₅ [annealed mixtures of Na₂O, Li₂O, and Ta₂O₅, Na : Li : Ta = 6.6 : 1.1 : 1, Ni-cylinder, 1000°C, 75 d] as well as Na₅NbO₅ [annealed mixtures of Na₂O, Li₂O, and Nb₂O₅, Na : Li : Nb = 6.6 : 1.1 : 1, Ni-cylinder, 1000°C, 75 d] have been prepared. Single crystal data show that both isotypic oxides represent a deformed variant of the NaCl-type of structure [Na₅TaO₅: 1154 from 1250 I₀ (hkl), four-cycle diffractometer Philips PW 1100, ω2-θ scan, Ag? Kα , R = 4.88%, space group c2/c with a = 629.3(1) pm, b = 1025.4(2) pm, c = 1004.6(2) pm, b? 106.80(2)°, z = 4 and Na₅NbO₅: 998 from 1247 I₀(hkl), four-cycle diffractometer Philips PW 1100, ω-2θ scan, Ag? Kα , R = 8.58% and R_w = 7.67%, space group C2/2 with a = 629.1(1) pm, b = 1024.4(2) pm, c = 1004.2(2) pm, b? = 106.80(2)°, Z = 4]. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, the latter derived from Mean Effective Fictive Ionic Radii, MEFIR, as well as Charge Distribution, CHARDI, are calculated.     

Die Schwingungsspektren und Kraftkonstanten der Anionen MoOF–5 MoOF2–5, MoF–6 und WOF–5

Inhaltsübersicht. Die Schwingungsspektren der Verbindungen CsMoOF₅, MWOF₅ (M = K, Rb, Cs), K₂MoOF₅, K₂MoOF₅ · H₂O, K₂MoOF₅ · KHF₂ und MMoF₅ (M = K, Cs) wurden aufgenommen und zugeordnet. Aus den so ermittelten Normalschwingungsfrequenzen wurden für die Ionen MoOF₅^–, WOF₅^–, MoOF₅^2– und MoF^–₅ Kraftkonstanten nach einem modifizierten Valenzkraftfeld berechnet. Anhand der erhaltenen Werte der Valenzkraftkonstanten werden die Bindungs-verhältnisse diskutiert. Vibrational Spectra and Force Constants of the Anions M0OF₅^–, MoOF₅^2–, MoF^–₆, and WOF₅^– Abstract. The vibrational spectra of CsMoOF₅, MWOF₅ (M = K, Rb, Cs), K₂MoOF₅, K₂MoOF₅ · H₂O, K₂MoOF₅ · KHF₂, and MMoF₅ (M = K, Cs) have been recorded and assigned. The vibrational frequencies were used to calculate MVFF constants for the ions MoOF₅^–, WOF₅^–, MoOF₅^2–, and MoF^–₆. The stretching force constants are discussed relative to the bond properties.     

Der Sättigungsdruck von NbBr5 und Tal5

Sublimation Pressure of NbBr₅, NbI₅, and TaI₅ The sublimation pressure of NbBr₅, NbI₅ and TaI₅ has been determined by a spectralphotometric method: . The vapour pressure of NbI_5,1 is equal to log \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\,{\rm = }\, - \frac{{4653}}{{\rm T}}\, + \,5.43 $\end{document}. All the pressure are given in atm. The melting point of NbI₅ is 673 ± 1 K.     

Struktur und Eigenschaften von 5-epi-Flavoxanthin und 5-epi-Chrysanthemaxanthin

Structure and properties of 5-epi-flavoxanthin and 5-epi-chrysanthemaxanthin The absolute configurations of 5-epi-flavoxanthin ( 6 ) and 5-epi-chrysanthemaxanthin ( 7 ) prepared by acid catalysed rearrangement of semi-synthetic lutein epoxide 5 are shown to be (3S, 5S, 8R, 3′R, 6′R) and (3S, 5S, 8S, 3′R, 6′R), respectively. Contrary to published data [5] the relationship of the polyene chain and H₃(18) on the dihydrofurane ring is cis for the pair of stereoisomers having a Δδ = δ (H? C(7)) ? δ (H? C(8)) = 0,22 ppm and ³J ≡ 0. These conclusions are in full accord with the chiroptical data.     

Lävulinsäureanilid und 5-Hydroxy-5-methyl-1-phenyl-2-pyrrolidon

The hitherto unknown tautomer of levulinic acid anilide (Ia), 5-hydroxy-5-methyl-1-phenyl-2-pyrrolidone (IIa), has been obtained by filtration of a chloroform solution of I a through acid ion-exchange columns. Ia and IIa show typical differences in NMR., IR. and MS. that can be used for their detection and determination in mixtures. Both tautomers are stable at room temperature in solid state and in neutral solutions but are equilibrated in acidic and basic solutions.     

Die Pyridinaddukte der Goldhalogenide. 2. Darstellung,Eigenschaften und Kristallstruktur von AuCl · NC5H5 und Aul · NC5H5

Pyridine Adducts of the Gold Halides. 2. Synthesis, Properties, and Crystal Structure of AuCl · NC₅H₅ and AuI · NC₅H₅ AuCl · py is formed by the reaction of AuCl · S(CH₂C₆H₅)₂ with pyridine in absolute Ethanol. AuI · py can be obtained from AuI and pyridine in toluene. Both compounds are sensitive to light and thermically instable. AuI · py decomposes already above ?30°C. AuCl · py crystallizes monoclinic with 16 formula units in the space group C2/c, AuI · py is orthorhombic with the space group Pnnm and 8 formula units per unit cell. The structures of the adducts are built up by linear Au(py)₂ and AuX₂ groups, which are linked together to tetranuclear, chainlike complexes AuX₂? Au(py)₂? Au(py)₂? AuX₂ by weak gold-gold bonds. (AuI · py)₄ forms a linear Au₄ chain and possesses nearly the symmetry D_2h. The shortest Au-Au distance being 299.0 pm. In the centrosymmetrical (AuCl · py)₄ an Au₄-zig-zag chain with Au? Au distances of 324.9 and 341.6 pm is observed. The gold-ligand bond lengths are: AuCl · py: Au? Cl = 228 pm, Au? N = 209 pm; AuI · py: Au? I = 254.4, Au? N = 202 pm. The IR spectra and the luminescence properties are discussed.     

5-Ethylthiomethyl- und 5-Ethylsulfonylmethylpyrimidine

In 2,4-dichloro-5-ethylthiomethylpyrimidines3a, b and in (2,4-dichloro-5-pyrimidinylmethyl)ethyl sulfones5a, b, resp., by reaction with ammonia, diethyl-amine, isopropylamine, sodium methanolate and sodium ethylthiolate, resp., the halogen atoms have been substituted by amino, methoxy or ethylthio groups, resp., and thus the compounds4a–4r and5c–5f have been obtained.

     

Gas-Chromatographie und Massenspektrometrie der Trimethylsilyl-enoläther von 5α- und 5β-Cholestan-3-on

Trimethylsilyl-enolethers of 5α- and 5β-cholestan-3-on were investigated by gas chromatography and mass spectrometry. These derivatives are readily prepared and well suited for gas chromatographic analysis. In the mass spectrum they show fairly intense fragmentation, which appears to be characteristic for some structural elements in the surroundings of the functional group (excluding stereochemistry). This fragmentation may be useful for the structure elucidation of 3-oxo-steroids and related compounds. For comparison purposes the corresponding enolacetates were also investigated.     

Stereospezifische Synthese des Cancerostatikums 5′-Desoxy-5-fluor-uridin (5-DFUR) und seiner 5′ -deuterierten Derivate

Stereospecific Synthesis of the Anticancer Agent 5′-Deoxy-5-fluorouridine and its 5′-deuteriated Derivatives 5′-Deoxy-5-fluorouridine (5′-DFUR) has been obtained in high yield and purity by Stereospecific condensation of the anomeric 5¨deoxy-1,2,3-tri- O-acetyl-D-ribofu-ranose with bis(trimethylsilylated)-5-fluorouracil in the presence of trimethylsilyl trifluoromethanesulfonate, and by subsequent cleavage of the acetate protecting groups. A minor by-product of the synthesis, the α-anomeric nucleoside is produced by a (β-α)-epimerization, a procedure which is catalyzed by trimethylsilyl trifluoromethanesulfonate. The corresponding 5′-deuteriated, and 5′,5′-dideuteriated nucleosides have also been synthesized using an analogous way. The synthesis of the sugar components of the latter nucleosides - starting from D-ribose, D-xylose and D-glucose -is also described.     

5-Methylthio-, 5-Methylsulfinyl- und 5-Methylsulfonyluracil

Zusammenfassung 5-Methylthiouracil wird auf verschiedenen Wegen durch Ringschlußreaktionen von Formylmethylthioessigester bzw. Derivaten mit S-Methylisothioharnstoff oder Thioharnstoff und Hydrolyse des primär gebildeten 2,5-Di-(methylthio)-4-oxypyrimidins bzw. 5-Methylthio-thiouracils dargestellt.Oxydation mit Peressigsäure führt zu 5-Methylsulfinyl- und 5-Methylsulfonyluracil. 5-Methylsulfonyluracil kann auch durch Oxydation von 2,5-Di-(methylthio)-4-oxypyrimidin und 5-Methylthio-thiouracil gewonnen werden.Herrn Prof. Dr.F. Wessely in freundschaftlicher Verehrung zu seinem 70. Geburtstag gewidmet.     

Synthese und Eigenschaften von Pentafluorophosphaten,YPF5− (Y = OR,NHAr), und PF5 · Amin-Addukten,PF5 · HNR2

Synthesis and Properties of Pentafluorophosphates, YPF₅^? (Y = OR, NHAr), and PF₅-Amine Adducts, PF₅ · NHR₂ In the presence of secondary amines instead of hexafluorophosphates, PF₆^?, PF₅-amine adducts, PF₅ · NHR₂, are obtained by the reaction of PCl₅ with alkylammonium fluorides in acetonitrile. The additional presence of alcohols or phenol leads to the formation of alkoxy- or aroxypentafluorophosphates, ROPF₅^?. The PF₅-amine adducts can be converted into ROPF₅^? or arylimidopentafluorophosphates, ArNHPF₅^?, resp., by treating with alcohols or aryl amines, resp.     

Benzooxaza- und Benzodiaza-λ3-phosphole und deren Reaktion zu spirocyclischen λ5-Phospholen

Benzooxaza- and Benzodiaza-λ³-Phospholes and their Conversion to Spirocyclic λ⁵-Phospholes 2,3-Dimethyl-1,3,2λ³-benzooxazaphosphole and 1,2,3-trimethyl-1,3,2λ³-benzodiazaphosphole are obtained by transamination of methylbis(dimethylamino)phosphane with N-methyl-o-aminophenol and N,N′-dimethylamino-o-phenylenediamine. These compounds are converted by oxidation and disproportionation reactions to spirocyclic λ⁵-phospholes. The crystal structure of 2-methyl-2,2′-spirobi(1,3-dimethyl-1,3,2λ⁵-benzodiazaphosphole) is established and a trigonal bipyramidal geometry of the molecule has been found.     

Additionen von SF5Cl und TeF5Cl an 〈CC〉 Doppelbindungen

Addition of SF₅Cl and TeF₅Cl on 〈C?C〉 double bonds Addition of SF₅Cl on 〈C?C〉 double bonds is investigated in a few examples. The results indicate a radical mechanism, in which the SF₅· free radical attacks the double bonds first. This is in agreement with many earlier findings. The direction of the addition is not changed by sterical influences. Sterically strained derivatives such as (SF₅)₂CH? CF₂Cl and SF₅(CF₃)₂C? CH₂Cl are obtained. In a single case the addition of TeF₅Cl on CH₂?CF₂ was possible, but the analogous reaction with SeF₅Cl was unsuccessful.