Within this thesis, the analysis and hence the better comprehension of the chemical bond within metal–element compounds is the central topic. By use of various DFT methods a selection of M–E interactions have been modeled and analyzed via Bader’s QTAIM, the ELF and NBO techniques. Special focus was set on a series of transition metal borylene and carbene complexes, and the Li–C bonds as representatives for main group organometallics. Therefore, this thesis is split into three parts:(I) An introduction reviewing the quantum chemical machinery as well as the analysis tools applied for the evaluation of chemical bonds. (II) Within the second part the chemical interactions taking place in transition metal complexes are studied focusing on borylenes and cognate carbenes. (III) In Part III, a broad overview of the appropriate modeling and nature of the Li–C bond as well as intermolecular interactions in methyllithium is provided. / Im Zentrum dieser Arbeit stand die Analyse von Metall–Element Wechselwirkungen, um ein tieferes Verständnis der chemischen Bindung zu erlangen. Unter Verwendung verschiedener DFT Methoden wurde eine Serie von M–E Bindungen modelliert und anschließend mittels Baders QTAIM, der ELF und dem NBO Ansatz analysiert. Im Fokus standen hierbei besonders Borylen und Carben Komplexe, sowie die Li–C Bindung stellvertretend für Organometallverbindungen der Hauptgruppen. Folglich gliederte sich die vorliegende Arbeit sich in drei Teile: (I) In einem einführenden Kapitel wurden die quantenchemischen Methoden sowie die verwendeten Techniken zur Bindungsanalyse vorgestellt. (II) Innerhalb des zweiten Teils wurden chemische Wechselwirkungen in Übergangsmetallkomplexen untersucht, im Besonderen in Borylen und gleichartigen Carben Verbindungen. (III) Teil III bot einen weitgefächerten Überblick über Modellierung und Natur der Li–C Bindung sowie der intermolekularen Wechselwirkungen in Methyllithium als Beispielverbindung.

<p> The reactions of methyllithium and phenyllithium with the iminium chloride, [(2R,3S)-2,3-dihydroxy-3-(6,7 -dimethoxy-3,4-dihydroisoquinolin-1-yl)]propionate hydrochloride, 34 as a means of preparing enantiomerically pure compounds are described. These reactions afford a single product in high yield. The nmr spectra of the products, 1-(1 ,2,3-trihydroxy-3,3-dimethylpropyl)-1 ,2,3,4-tetrahydro-6,7 -dimethoxy-1- methylisoquinoline 54 and 1-( 1,2,3-trihydroxy-3,3-diphenylpropyl)-1,2,3,4-tetrahydro-6,7- dimethoxy-1-phenylisoquinoline 62, are discussed and an explanation is given to account for the diastereoselectivity of the reaction. By this method, enantiomerically pure compounds bearing a quaternary centre at C-1 of the tetrahydroisoquinoline system may be prepared. Oxidative degradation of the hydroxylated side chain of compound 62 has led to the preparation of several other new compounds. </p> <p> The usefulness of the t-butoxycarbonyl group as a selective protecting group for nitrogen in the preparation of 2-t-butyloxycarbonyl-1,2,3,4-tetrahydro-1-(1,2,3- trihydroxy-3,3-dimethylpropyl)-6,7-dimethoxy-1-methylisoquinoline 59 is described. It has advantages over the ethoxycarbonyl group in that it not only selectively protects the amino group but also is easy to remove by short treatment with trifluoroacetic acid and water at room temperature. Treatment of 59 with sodium periodate afforded the aldehyde, 1-formyl-2-t-butyloxycarbonyl-1,2,3,4-tetrahydro-6,7-dimethoxy-1-methylisoquinoline, 60. An attempted oxidation of the aldehyde 60 to the acid is also described. </p> <p> A review of recent methods of inducing chirality at C-1 of the tetrahydroisoquinoline system is given in the Introduction. </p> / Thesis / Master of Science (MSc)