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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 375-381 
    ISSN: 1434-1948
    Keywords: Fluorine ; Silicon ; Ab initio calculations ; Donor-acceptor systems ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantum chemical calculations at the ab initio level indicate that Lewis donors such as amine or water form weak donor-acceptor complexes with fluoro-substituted silanes. The strength of the donor-acceptor formation increases with increasing degree of fluorine substitution. Amine and water form strong adducts only for tetrafluorosilane. The higher element homologues of Lewis donors, such as phosphane and sulfur dihydride, do not in essence coordinate. A considerable role in donor-acceptor formation is exerted by chelation effects which impose intramolecular interactions on functionalized ligands. The corresponding structures are explored.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 951-955 
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Phosphorus ; Strained molecules ; Substituent effects ; Pericyclic reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: According to quantum chemical calculations at an ab initio level parent 1,2-diphosphete is slightly more stable than its corresponding 1,4-diphosphabutadiene structural isomer. The quantum chemical calculations indicate that substituents at phosphorus and to a much less extent at carbon exert strong influences on the equilibrium geometries of 1,2-diphosphete structures: π donors at phosphorus strongly elongate the P-P bond while electronegative substituents at phosphorus increase the interflap angle of the four-membered ring systems, bringing an envelope conformation to the fore. The lengthening of the P-P bond gives rise to a Möbius-type delocalization within the ring moiety.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Chelates ; Donor-acceptor systems ; P ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mono- and bidentate chelation of the main-group elements silicon, germanium, tin, and lead through the phosphorus atoms of the diphosphanylmethanide ligand has been studied by means of quantum chemical methods. In accord with experimental investigations, the species are found to adopt a ψ-tbp conformation of high flexibility. The various distortional modes causing the axial and equatorial positions to become equivalent have also been investigated. In addition, the bonding situations in the electronically related bis(diamino)- and the higher element homologue bis(diarsanyl)methanide ligand systems have been studied. The bonding situation in the hitherto experimentally unknown bis(diamino)methanide ligands is predicted to be similar to that in bis(amidinate) complexes. An analysis of the electron distributions (natural bond orbital population analysis) in these compounds reveals that the central main-group element is positively charged and weakly chelated by the surrounding ligands.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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