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  • 1
    Electronic Resource
    Electronic Resource
    Photochemistry of N-Phthaloylcysteine Derivatives: Multiplicity-Directed Regioselective CH Activation (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 1388-1394 
    Details
    ISSN: 0947-6539
    Keywords: amino acids ; C-H activation ; electron transfer ; photochemistry ; state selectivity ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photochemistry of the methyl esters of N-phthaloylcysteine derivatives 1b-5b was studied. The results are remarkable, because they prove a pronounced, multiplicity-controlled regioselectivity of the initial CH activation step. From substrates 1b-4b the benzazepine-1,5-dione 6 was produced exclusively by the singlet path. The formation of compound 6 is initiated by a γ-H abstraction; this was demonstrated by deuterium labeling experiments. The penicillamine derivative 5b was unreactive in the singlet manifold. From substrates 1b-3b and 5b the thiazinoisoindoles 7-9 and 11 were produced exclusively by the triplet path. The sterically hindered S-isopropylcysteine derivative 4b also furnished this product type (10) as a proportion of the products in the singlet manifold. These annulation products result from a primary photoinduced electron-transfer (PET) step followed by heterolytic ∊-H activation. The mechanistic scenario was elucidated by quenching and sensitization experiments. An interplay of CH activation steps and electron back-transfer is probably responsible for this type of spin selectivity.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19960021110
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and Reactions of Optically Active Bridged Deoxyfuranose Derivatives (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 683-688 
    Details
    ISSN: 1434-193X
    Keywords: Bridged furanose derivatives ; Resolution ; Dimerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of the bridged methyl furanosides 1, 3 and 5 with dilute acid furnishes the corresponding deoxyfuranose derivatives 2, 4 and 6. The trans-substitution pattern of the tetrahydrofuran ring was established by X-ray structural analysis of 2 and by comparison of the 1H-NMR spectra. A new resolution procedure for rac-3 via the dicamphanoates (+)-7 and (-)-7 is reported. The hemiacetals (+)-6 and (-)-6 dimerize readily under elimination of water in chloroform to give the bridged disaccharides (+)-8 and (-)-8, respectively.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Selective Reactions, Resolution and Absolute Configuration of Bridged Hydroazulenes (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2651-2657 
    Details
    ISSN: 1434-193X
    Keywords: Functionalized hydroazulenes ; Wittig reaction ; Selective additions ; Resolution ; X-ray analyses ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of the bridged oxepine (±)-1 with a large excess of powdered sodium methoxide in Et2O or with triphenylphosphonium methylide leads to the functionalized hydroazulenes (±)-2 (69%) and (±)-3 (81%). Regioselective and stereoselective cyclopropanation of (±)-2 leads to the dibromocyclopropane derivative (±)-4. Epoxidation gives the epoxides (±)-5 and (±)-6. The resolution of the hydro-azulenone (±)-2 is achieved by fractional crystallization of the quinine salt (-)-8 of the corresponding mono acid (±)-7. The absolute configuration of (+)-7 is established by X-ray analysis of the quinine salt (-)-8.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    DCNQI Anion-Radical Salts with Bisammonium Cations (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1653-1660 
    Details
    ISSN: 1434-193X
    Keywords: Conducting materials ; Radical ions ; Crystal structures ; Electrochemistry ; Dications ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-anion salts have been prepared by electro-crystallization from seven 2,3- and 2,5-disubstituted DCNQIs and the quaternary dications (AMM2+) HMED, DMBP, EBP, and EBBT. The black compounds adopt the stoichiometry DCNQI/dication = 3:1. The crystal-structure analysis of two of these radical salts reveal skewed (zigzag, trimerized) stacks of DCNQI molecules separated by sheets of dications. Specific interactions between DCNQI anions and dications are absent. The effect on the stacking of the DCNQI units of the two positive charges in the dications which are held apart at a defined separation is discussed. The salts are shown to be semiconductors with powder conductivities of 10-2 to 10-5 S cm-1.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    The Reaction of Dimethyl 10-Oxo-3,6-hexanooxepine-4,5-dicarboxylate with Sodium Methoxide/Methanol - A Reinvestigation (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 507-508 
    Details
    ISSN: 1434-193X
    Keywords: Oxepines ; Bicyclopentyl derivatives ; X-ray analysis ; Correction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of the title compound 1 with sodium methoxide in ether in the presence of methanol leads to the bicyclopentyl derivative 3. The structure of 3 was established by X-ray analysis. The structure 2 proposed earlier has to be corrected in favour of 3.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    A Zwitterionic Distannene and Two (RSnX)4 Cages with an Unusual Arrangement of the Sn4X4 Cluster Atoms (R = tBu3Si, × = Se, Te) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1333-1336 
    Details
    ISSN: 1434-1948
    Keywords: Tin ; Silicon ; Chalcogens ; Cluster compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of tin(II) chloride with RNa(THF)2 (R = tBu3Si) in THF at -30 °C led to a complex reaction mixture, from which the compounds R4Sn4(THF)2, R2SnSnR2 (5), R-R (7), and a brownish black compound 6 were isolated. In toluene as solvent, the zwitterionic distannene 5 was obtained together with 7 and 6 which upon treatment with Et3PX, furnished the cluster compounds (RSnX)4 (10: × = Se; 11: × = Te). The X-ray structure analyses of the isotypic compounds 10 and 11 revealed that the tin atoms occupy the corners of an undistorted tetrahedron with weak tin-tin interactions. The chalcogen atoms form a plane which bisects the Sn4 tetrahedron.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    A Novel Route to Formaldehyde and Thioformaldehyde Rhodium Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1605-1617 
    Details
    ISSN: 1434-1948
    Keywords: Rhodium ; Carbenoide metal complexes ; Formaldehyde complexes ; Thioformaldehyde complexes ; Cyclopentadienyl complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The acetoxymethyl rhodium compounds [(η5-C5R5)Rh(CH2OAc)(L)I] (4, 13-16) which were prepared from the chloromethyl derivatives [(η5-C5R5)Rh(CH2Cl)(L)I] and sodium acetate in benzene/acetic acid as solvent, reacted with AgPF6 to give the chelate complexes [(η5-C5R5)Rh{ĸ2-C,O-CH2OC(Me)O}(L)]PF6 (19-23) in excellent yields. Treatment of these complexes with KOH in methanol led to the elimination of the acetyl group and to the formation of the formaldehyde compounds [(η5-C5R5)Rh(η2-CH2O)(L)] (24-27). The related thioformaldehyde complexes [(η5-C5Me5)Rh(η2-CH2S)(L)] (46, 47) and [(η5-C5H5)Rh(η2-CH2S)(PMe3)] (50) were obtained on a similar route. Studies on the reactivity of the formaldehyde derivatives revealed that the Rh-CH2O bond is rather labile and the CH2O ligand easily converted to a CO group.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Die Struktur des 2,6-Diphenylhomotropilidens (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 90-103 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Structure of 2,6-DiphenylhomotropilideneThe structure of the title compound 1 was determined be means of NMR spectroscopy as well as by force field calculations and X-ray structure analysis. The results prove the ring system to be remarkably flexible for the free molecule, the molecule in solution and in the crystalline state. Furthermore, it shows the relation between conformation and ring inversion with increasing molecular interactions. The variation of the structure angles α and β follows from the relation α = 1.4 β and encloses the transition state of the ring inversion. Under the same conditions the seven-membered ring is more puckered than the unsubstituted homotropilidene. The phenyl fragments may prefer coplanar orientations to the double bonds of the seven-membered ring, but the torsion of these groups requires only little energy.
    Notes: Die Struktur der Titelverbindung 1 wurde durch NMR-Spektroskopie, durch Kraftfeldrechnungen und durch eine Röntgenstrukturanalyse bestimmt. Die Ergebnisse beweisen sowohl für die Struktur ohne Medium als für die Struktur in der Lösung und im Kristall eine erhebliche Flexibilität des Ringsystems und zeigen die Zusammenhänge zwischen Konformation und Ringinversion bei zunehmenden intermolekularen Wechselwirkungen. Die Variation der Strukturwinkel α und β folgt der Beziehung α = 1.4β. Sie schließt damit den Übergangszustand der Ringinversion ein. Die Aufwellung des Siebenrings ist unter vergleichbaren Bedingungen größer als im unsubstituierten Homotropiliden. Die Phenylringe bevorzugen zwar koplanare Orientierung zu den Doppelbindungen des Siebenrings, jedoch wird für die Torsion der Substituenten nur ein geringer Energieaufwand benötigt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801130112
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  • 9
    Electronic Resource
    Electronic Resource
    Chemische und magnetische Eigenschaften der Bariumfluorometallate(II) Ba2MF6 mit M = Zn, Cu, Ni Co, Fe (1967)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 353 (1967), S. 1-12 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The compounds Ba2ZnF6 (colourless), Ba2CuF6, (colourless), Ba2NiF6 (yellow), Ba2CoF6 (lilac) and Ba2FeF6 (colourless) being representative for fluorometallates of the kind A2IIMIIF6 were prepared from the melts of the corresponding binary components at 1100-1250 °C, yielding small square platelets. All compounds have very similar structures2. The molar volumes of the complexes are about 12% smaller than that of the component mixtures. There could not be observed any reaction between BaF2 and MnF2 or MgF2.Ba2ZnF6 is diamagnetic (χm = -123 · 10-6[cm3 · mol-1]), Ba2CuF6 paramagnetic (μ = 1.85 B.M.; θ = +15°K). From the e. s. r. spectrum a gyromagnetic factor g = 2.20 is deduced. Ba2NiF6 and Ba2CoF6 show antiferromagnetic behaviour below 200-250°K; at temperatures higher than 300°K they become paramagnetic (μ = 3.76 B.M., θ = -385° and μ = 5.22 B.M., θ = -115°).
    Notes: Als Vertreter 2,2-wertiger Fluorometallate vom Typ A2IIMIIF6 wurden die Verbindungen Ba2ZnF6 (farblos), Ba2CuF6 (farblos), Ba2NiF6 (gelb), Ba2CoF6 (fliederfarben) und Ba2FeF6 (farblos) aus Schmelzen der binären Komponenten (1100-1250°C) dargestellt. Die Verbindungen entstehen in Form kleiner quadratischer Blättchen und haben weitgehend die gleiche Struktur2. Im Vergleich mit den Gemengen der binären Komponenten sind die Molvolumina um etwa 12% kleiner. Umsetzungen zwischen BaF2 und MnF2 bzw. MgF2 wurden nicht erhalten.Ba2ZnF6 ist diamagnetisch mit χMol = -123 · 10-6[cm3 · Mol-1]. Ba2CuF6 ist paramagnetisch mit μ = 1,85 B. M. und θ = +15°. Aus dem E.S.R.-Spektrum ergibt sich der gyromagnetische Faktor zu g = 2,20. Ba2NiF6 und Ba2CoF6 sind unterhalb 200-250°K antiferromagnetisch, oberhalb 300°K paramagnetisch mit μ = 3,76 B.M. (θ = -385°) bzw. μ = 5,22 B.M. (θ = -115°).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19673530102
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  • 10
    Electronic Resource
    Electronic Resource
    Kristallstrukturen der Bariumfluorometallate(II) Ba2MF6 mit M = Zn, Cu, Ni, Co, Fe (1967)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 353 (1967), S. 13-25 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The crystal structures of Ba2ZnF6, Ba2CuF6, Ba2NiF6, Ba2CoF6 and Ba2FeF6 have been determined. These compounds are isostructural (Bi2NbO5F structure) and can be described by the formula (BaF)2[MF4], the complex anions [MF4] forming infinite layers of the kind ∞2[MF4/2F2] and the central atoms M being co-ordinated octahedrally. In all cases the co-ordination octahedra are distorted. The kind of distortion markedly depends upon the central atom: Ba2CuF6 contains tetragonally flattened, Ba2CoF6 tetragonally elongated MF6 octahedra (JAHN-TELLER effect).
    Notes: Die Kristallstrukturen von Ba2ZnF6, Ba2CuF6, Ba2NiF6, Ba2CoF6 und Ba2FeF6 wurden bestimmt. Die Verbindungen sind strukturchemisch durch die Formel (BaF)2[MF4] zu beschreiben (Bi2NbO5F-Typ), wobei die komplexen Anionen [MF4] einen zweidimensional unendlichen Verband ∞2[MF4/2F2] mit oktaedrisch koordinierten Zentralatomen M bilden. Die Koordinationsoktaeder der Zentralatome sind in allen Fällen deformiert und zeigen charakteristische Unterschiede. Ba2CuF6 enthält stark gestauchte, Ba2CoF6 dagegen gestreckte MF6-Oktaeder (JAHN-TELLER-Effekt).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19673530103
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