Wechselspiel zwischen Struktur, elektronischer Situation und Reaktivität stark polarer Bindungen in industrierelevanten Reagenzien

Abstract

The present work is focused on gaining a better understanding of the bonding situation of polar silicon-oxygen and silicon-carbon bonds as well as highly polar metal-carbon bonds, as they occur in commercially available as well as industrially applied compounds. The questions arising in this context were not only approached experimentally through synthetic investigations and analytical structure elucidations in the solid state and in solution but were also examined from a theoretical perspective through the use of quantum chemical calculations and bond analysis tools. For this purpose, the same type of bond was considered in structurally similar molecules in order to be able to draw conclusions about the electronic situation in each case on the basis of a relative comparison. In this way, it was not only possible to develop new mechanistic models of Si–C-bond cleavage reactions, but also to gain unique insights into the electronic structure of Si–O- and Si–C-bonds. The findings obtained in this way can be used as a stepstone for new approaches and strategies for the effective degradation of silicone compounds and are thus of elementary conceptual importance. Furthermore, new synthetic routes to both highly labile organosilanes and an enantiomerically enriched silane could be established and a previously unsuccessful functionalization of aminometalated species could be achieved. Through a combination of high-resolution X-ray diffraction experiments, quantum chemical calculations and bond analysis tools, previously unknown stabilization effects, as they occur in presumably all organometallic compounds, could be uncovered, investigated as well as classified for the first time. The knowledge gained from this gives a new view on the structure-reactivity relationship of organometallic compounds. In the last part of this work, the structure of two Turbo-Grignard reagents in the solid state and in solution was elucidated for the first time. These structural data were then used as a basis for quantum chemical modelling of a magnesium–bromine-exchange. The knowledge gained from this not only explains the extraordinary reactivity of these reagents, but also shows why and how a general influencing of the reactivity of organometallic reagents by anionic components is possible.