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  • 1
    ISSN: 1434-193X
    Keywords: Hydroxyalkenoic acids ; Hydrogen bonds ; Crystal engineering ; Molecular assemblies ; Scanning force microscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The substituted 6-hydroxy-trans-3-hexenoic acids 2-4 have been prepared by a template coupling reaction between (butadiene)zirconocene, W(CO)6, and cyclobutanone, cyclodecanone, or cyclododecanone, respectively, followed by hydrolytic/oxidative demetallation of the resulting metallacyclic zirconoxycarbene tungsten complexes. The hydroxyalkenoic acids 2-4 have been found to form two novel fundamental types of associated supramolecular structural arrays in the solid state through intermolecular hydrogen bonding, which have been characterized by X-ray diffraction analysis. The cyclobutanone-derived compound 2 exhibits an infinitely extending sheet-like structure, which is composed of symmetrically alternating interconnected 12- and 36-membered rings, each being constructed from the functional groups or frameworks of four individual molecules of 2. In contrast, the cyclodecanone-derived compound 3 adopts a ribbon-type structure composed of C2-symmetrically arranged symmetry-equivalent 15-membered rings, each containing the functionalities from three individual molecules of 2. On the basis of scanning force microscopy studies, the cyclododecanone-derived compound 4 would appear to have a similar structure in the solid state. The structural features of the molecular assemblies that are formed by intermolecular hydrogen bonding of compounds 2-4 in the solid state are selectively controlled by the size and favoured conformations of the spiro-anellated carbocyclic rings at C6 of the 6-hydroxy-trans-3-hexenoic acid carbon chain.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-1948
    Keywords: Group-5 bent metallocene cation complexes ; (Butadiene)tantalocene cation ; (s-trans-η4-Butadiene)metal complex ; Ethene polymerization ; Metallocenes ; Homogeneous catalysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Butadiene)TaCp*Cl2 (6) was treated with CpNa to yield (η2-butadiene)TaCp*CpCl (7). Subsequent reaction with [Cp2ZrCH3+][CH3B(C6F5)3-] resulted in transfer of the chloride ligand from tantalum to zirconium with formation of the [(s-trans-η4-butadiene)TaCp*Cp]+ cation [8, with CH3B(C6F5)3- anion]. Complex 8 was characterized spectroscopically and by an X-ray crystal structure analysis. The group-5 [(s-trans-η4-C4H6)TaCp*Cp]+ bent metallocene cation complex 8 reacts with ketones (acetone, adamantanone) to yield the corresponding seven-membered 2-tantalatetrahydrooxepine cation complexes (9, 10). 1-Cyanoadamantane reacts with 8 to yield the 2-tantala-3,6-dihydro-2H-azepine cation system 11. Activation of 8 with methylalumoxane gives an active ethene polymerization catalyst.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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