Untersuchungen zu Oligogallanen mit Gruppe 15 Substituenten

Abstract

On the present thesis the focus was set on the synthesis and structure investigation of novel subvalent oligogallanes. Since gallium has an electron deficiency and acts as a strong lewis acid it is not trivial to get low oxidation state compounds. Disproportion reactions often lead to Ga(+III) and elemental Ga(0), so it is essential to avoid oxygen, water and in many cases strong donor solvents like THF. Many reactions were observed where the mere warming to room temperature led to undesired byproducts. A convenient method to get access to gallium in low oxidation states is the sonicated “GaI”. It was used for most of the compounds presented in this work. In the first part neutral and anionic phosphorous compounds are used to stabilize and shield the sensitive gallium cores from decomposition. Suitable ligands were di-tert-Butyl-, di-Phenylphosphanes or mixtures of them combined at one phosphor atom. In this manner several molecules could be synthesized with two to four gallium atoms. Two of the maintained structures contain three connected metal atoms with the oxidation states (II)-(I)-(II). In the second part novel nitrogen ligand compounds are described with special focus on amidinates in different coordination forms. In the given literature they are usually formed by deprotonation of dialkylamidines or by nucleophilic attack of BuLi derivates on carbodiimides. In this work the nucleophilic attack of alkyl- and silylamides on nitriles is compared and thereby the formation of two types of coordination to the gallium metal.