FU Berlin Digitale Dissertation
Peter A. Günther : Laserspectroscopical investigations and quantummechanical calculations on the mechanism of nucleophilic ipso substitutionreactions of molecular aggregates Laserspektroskopische Untersuchungen und quantenmechanische Berechnungen zum Mechanismus von nucleophilen ipso-Substitutionsreaktionen in molekularen Aggregaten
|Abstract| |Table of Contents| |More Information|

Abstract This work presents experimental investigations of nucleophilic substitution reactions and quantummechanical structure optimizations of molecular aggregates. This studies are performed to reveal detailed informations for the size and species selectivity of nucleophilic substitutions. The first part deals with experiments on mixed van der Waals aggregates. In a supersonic jet clusters of difluorobenzene and ammonia are prepared and ionized via resonant two-photon absorption (R2PI). In a time-of-flight mass spectrometer the produced cations are detected. By this method the influence of solvatation and size dependence is characterized. The second part deals with ab initio HF calculations on 1,n-difluorobenzene·NH3 and 1,n-difluorobenzene·(NH3)2 and the corresponding cations. Structures of the van der Waals clusters were fully minimized for inter- and intra-molecular degrees of freedom. The results of these calculations are expected to deliver new aspects of the role of isomers of clusters in nucleophilic substitution reactions.We evaluated different stable cluster isomers which could be responsible for the substitution reaction. The most important results of the substitution reactions in ionized difluorobenzene/ammonia clusters may be summarized as follows: The reactivity does not depend on the position of the two fluoro-substituents at the aromatic ring. With all of the three difluorobenzenes a fluoroaniline cation and a ammonia dimer cation are observed as the products of the same precursor (1,n-difluorobenzene.(NH3)2)+.

Table of Contents Download the whole PhDthesis as a zip-tar file or as zip-File For download in PDF format click the chapter title Titelblatt und Inhaltsverzeichnis 1. Einleitung und Problemstellung 2. Molekulare Aggregate 2.1 Intermolekulare Wechselwirkungen 2.2 Relaxationsprozesse 3. Experimentelle Methoden 3.1 Erzeugung von van der Waals-Clustern im Molekularstrahl 3.2 Resonante 2-Photonen Ionisation 3.3 Die Apparatur 4. Theoretische Grundlagen der ab initio-Quantenchemie 4.1 Was versucht die ab initio-Quantenchemie 4.2 Hartree-Fock Methoden 4.3 Die Bedeutung der Basisfunktionen 4.4 Die Korrelationsenergie 4.5 Ab initio-Berechnungen von van der Waals-Clustern 5. Aromatische Substitutionsreaktionen 5.1 Elektrophile Substitutionen 5.2 Nucleophile Substitutionen 6. Ergebnisse 6.1 Meta-Difluorbenzol 6.2 Ortho-Difluorbenzol 6.3 Para-Difluorbenzol 6.4 Chlorfluorbenzole 7. Zusammenfassung 8. Anhang A Abkürzungsverzeichnis B Berechnete Strukturparameter des neutralen Clusters 6 C Berechnete Strukturparameter des kationischen Clusters 9 D Detaillierte Darstellung des Versuchsaufbaus Literaturliste

More Information:
Online available:	http://www.diss.fu-berlin.de/1999/8/indexe.html
Language of PhDThesis:	german
Keywords:	Clusters, Mass Spectrometry, Molecular Beams, Multiphoton Processes, Ion Molecule Reactions
DNB-Sachgruppe:	30 Chemie
Date of disputation:	16-Dec-1998
PhDThesis from:	Fachbereich Biologie, Chemie, Pharmazie, Freie Universität Berlin
First Referee:	Prof. Dr. Helmut Baumgärtel
Second Referee:	Prof. Dr. Eugen Illenberger
Contact (Author):	pegue@chemie.fu-berlin.de
Contact (Advisor):	baum@chemie.fu-berlin.de
Date created:	10-Feb-1999
Date available:	10-Feb-1999

 

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