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  • Articles: DFG German National Licenses  (4)
  • Al—Al bond  (2)
  • Crystal structure  (2)
  • 1
    ISSN: 1434-4475
    Keywords: 4-Benzoyl-5-phenylfuran-2,3-dione ; Dibenzoylacetic acid-N-carboxyamides ; Oxazin-2,4-dione ; Keto-enole tautomerism ; Semiempirical quantum chemical calculations ; Crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 4-Benzoyl-5-phenylfuran-2,3-dione (1) and the urethanes2 combine under loss of carbon monoxide yielding the open chain dibenzoylacetic acid derivatives3 and4. 3a, b only can be cyclized to the oxazinone5. The keto-enole tautomerism3 ⇌4 is further investigated with aid of semiempirical quantum chemical calculations, based upon the molecular geometry of3a, deduced from an X-ray study.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8773
    Keywords: Cu-desferrithiocin ; Crystal structure ; Superoxide dismutase activity ; Stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A Cu(II) complex of desferrithiocin fromStreptomyces antibioticus was prepared and characterized. The first shell atoms, including one nitrogen and four oxygens, were arranged around the copper in a square-planar pyramide. Due to the axially Jahn-Teller-distorted Cu-O distance at 224.7 pm, a distinct Cu2Zn2superoxide dismutase mimetic activity was measured. The Cu-complex survived 600 μM bovine serum albumin and the thermodynamic stability (pK=17.4) was not very different from that of Cu-EDTA. The electronic absorption properties, circular dichroism and electron paramagnetism were in accordance with those of the type-II copper species.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-2313
    Keywords: Aluminium ; indium ; Al—Al bond ; In—In bond ; benzoato bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Reactions of R2Al—AlR2 and R2In—InR2 with Benzoic Acid - Synthesis and Crystal Structure of R2Al(μ-H)(μ-O2C—C6H5)AlR2 and RIn(μ-O2C—C6H5)4InR [R = CH(SiMe3)2]Tetrakis[bis(trimethylsilyl)methyl]dialane(4) 1 reacts with benzoic acid by the oxidative cleavage of the Al—Al bond: The Al atoms are inserted into the O—H bond of the acid and the proton is reduced to a hydride anion. As shown by a crystal structure determination, the product 4 shown an unprecedented structure with both dialkylaluminium fragments unsymmetrically bridged by the hydrogen atom and a benzoato group. 4 can be described as a model compound for the first step of the hydrolysis of compounds with low-valent Al atoms as well as elemental aluminium itself. The diindane(4) analogue of 1 (2) and benzoic acid yield, however, elemental indium and mixed alkyl benzoato indium derivatives, from which bis(trimethylsilyl)methyldi(benzoato)indium 9 has been characterized by a crystal structure determination. 9 consists of a dimer with a remarkable cage structure, in which both monoalkylindium groups are interconnected by four benzoato-O,O′ bridges.
    Notes: Tetrakis[bis(trimethylsilyl)methyl]dialan(4) 1 reagiert mit Benzoesäure unter oxidativer Öffnung der Al—Al-Bindung, wobei sich formal die Al-Atome in die O—H-Bindung der Säure einschieben und das Proton zu einem Hydridion reduzieren. Die beiden Dialkylaluminium-Fragmente des daraus erhaltenen Produkts 4 werden, wie durch Kristallstrukturbestimmung gezeigt wird, in bisher unbekannter Weise durch das Wasserstoffatom und eine Benzoatogruppe unsymmetrisch miteinander verbrückt. 4 läßt sich als Modellverbindung für die erste Stufe der Hydrolyse von Derivaten mit niederwertigen Al-Atomen und elementarem Aluminium beschreiben. Das zu 1 analoge Diindan(4) 2 ergibt dagegen mit Benzoesäuren unter Abscheidung von elementarem Indium gemischte Alkyl-benzoatoindium-Verbindungen. Bis(trimethylsilyl)methyl-di(benzoato)indium 9 wird kristallstrukturanalytisch untersucht; es liegt als Dimeres mit einer Käfigstruktur vor, in der zwei Monoalkylindium-Reste über vier Benzoato-O,O′-Brücken miteinander verbunden werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 823-828 
    ISSN: 0044-2313
    Keywords: Al—Al bond ; insertion reaction with tert-butyl isocyanide ; trimeric cyano dialkyl alane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of the Trimeric [(Me3Si)2CH]2Al—CNTetrakis[bis(trimethylsilyl)methyl]dialane(4) 1 with an Al—Al bond reacts with tert-butyl isocyanide in the molar ratio of 1:2 within three days to give a mixture of several unknown products, from which the title compound 4 is isolated in a 26% yield by recrystallization from n-pentane. 4 is a trimer in the solid state via Al—C≡N—Al bridges showing a nine-membered Al3C3N3 heterocycle in a boat conformation. In contrary to the reaction with phenyl isocyanide the expected dark red product of the twofold insertion into the Al—Al bond under formation of a carbon-carbon single bond is detected only spectroscopically as a minor by-product.
    Notes: Tetrakis[bis(trimethylsilyl)methyl]dialan(4) 1 mit Al—Al-Bindung reagiert mit tert-Butylisocyanid im Molverhältnis 1:2 im Laufe von drei Tagen unter Bildung eines unübersichtlichen Produktgemisches, aus dem sich in 26% Ausbeute durch Umkristallisieren aus n-Pentan farblose Kristalle der Titelverbindung 4 isolieren lassen. Wie die Bestimmung der Kristallstruktur ergibt, liegt 4 im Festkörper als Trimeres mit Al—C≡N—Al-Brücken vor, und der sich ausbildende neungliedrige Al3C3N3-Heterozyklus weicht leicht von der Planarität unter Ausbildung einer Wannenkonformation ab. Das mit Phenylisontril hauptsächlich gebildete Produkt der zweifachen Insertion in die Al—Al-Bindung unter Knüpfung einer C—C-Einfachbindung wird hier nur in verunreinigter Form spektroskopisch nachgewiesen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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