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Dissertation angenommen durch: Universität Duisburg-Essen, Campus
Duisburg, Fakultät für Naturwissenschaften, Institut für Chemie,
2003-11-07
BetreuerIn: Prof. Dr. Hermann-Josef Frohn , Universität
Duisburg-Essen, Campus Duisburg, Fakultät für Naturwissenschaften,
Institut für Chemie
GutachterIn: Prof. Dr. Hermann-Josef Frohn , Universität
Duisburg-Essen, Campus Duisburg, Fakultät für Naturwissenschaften,
Institut für Chemie
GutachterIn: Prof. Dr. Helge Willner , Bergische Universität Wuppertal, Fachbereich Mathematik und Naturwissenschaften, Fachgruppe Chemie
Schlüsselwörter in Deutsch: Edelgase; Xenon; Arylxenon; NMR
Spektroskopie; Synthese; hypervalente Verbindungen;
Bis(pentafluorphenyl)xenon; Diarylxenon; Xenondifluorid; Xenonfluorid;
Xenon Kohlenstoff Bindung; Perfluoraryl; Lewisacidität
Schlüsselwörter in Englisch: noble gases; xenon; arylxenon; NMR
spectroscopy; synthesis; hypervalent compounds;
Bis(pentafluorophenyl)xenon; diarylxenon; Xenon difluoride; xenon
fluoride; xenon carbon bond; Perfluoroaryl; Lewis acidity
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Abstrakt in Englisch
The preparation and characterization of new molecular covalent
compounds with a xenon-carbon bond is described within the framework of
this thesis.
Pentafluorophenylxenon(II) fluoride and 2,4,6-trifluorophenylxenon(II)
fluoride are prepared by metathesis of arylxenon(II)salts and
tetramethylammonium fluoride in dichloromethane at -78 °C. These
asymmetric hypervalent molecules possess a weak and elongated
xenon-fluorine bond when compared to xenon difluoride. The high
polarity of the Xe-F bond enables the fluorine abstraction even with
weak Lewis acids. The fluorine-ligand in arylxenon(II) fluorides can
easily substituted, e.g. during the reaction with diarylcadmium the
corresponding diarylxenon(II) compounds are formed. Using that approach
bis(pentafluorophenyl)xenon(II), bis(2,4,6-trifluorophenyl)xenon(II)
and the asymmetric compound
(pentafluorophenyl)2,4,6-trifluorophenylxenon(II) are prepared and
characterized by multinuclear NMR spectroscopy. Further the preparation
of bis(pentafluorophenyl)xenon(II) starting from
pentafluorophenylxenon(II) fluoride or xenon difluoride and
pentafluorophenylsilanes with different Lewis acidities is
investigated. This procedure was also extended to perfluoroalkenyl or
perfluoroalkyl ligands. Pentafluorophenylxenon(II) chloride and
2,4,6-trifluorophenylxeon(II) chloride are prepared by conversion of
the corresponding Arylxenon(II) fluorides with trimethylsilyl chloride
while Pentafluorophenylxenon(II) cyanide is generated using
trimethylsilyl cyanide as a substrate. The reactions with
trimethylesilyl thiocyanide and -bromide did not yield
pentafluorphenylxenon(II) thiocyanide or bromide respectively. The NMR
spectra of the new arylxenon(II) compounds are discussed as well as
compared with NMR data from existing arylxenon(II) compounds. The
interpretation is supported by ab initio calculations on RHF level.
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