FWF - Polygermaniumchemie - Polygermanium chemistry

Due to the unusual property of sigma bond electron delocalization, long chains consisting of silicon atoms, so called polysilanes, are the subject of intense research since the 1960s. Also polystannanes, which are composed of tin atoms, possess this property and are thus studied for their potential as molecular conductors. For some reason chains made of germanium, the element between silicon and tin, were not recognized as a prime target of research. This strange fact reflects a general disinterest in germanium chemistry. For a long time germanium was considered to be a dull hybrid of silicon and tin, without having much chemical potential. Also our own work over the last years was focused mainly on the element silicon. Studying the chemistry of polysilyl anions and cations we were able to develop synthetic methods for the construction of structurally varied polysilane molecules. In connection to these studies we became interested in analogous chemistry of germanium. Quickly we recognized the unique qualities of the germanium compounds, which were not only chemically different but were found to differ also with respect to structural properties from the previously studied polysilanes. Investigations in collaboration with colleagues from Cork University College; Ireland revealed also a quite unusual thermolytic decomposition behavior in supercritical fluids. In one step our silylated germanium compounds decompose to nanowires possessing a crystalline germanium core covered by an amorphous siliconoxide surface. The planned studies of the project will, based on our experience with similar silicon compounds, explore the reactivity of analogous germanium compounds. Germylanions with and without additional silyl groups will be used as building blocks for larger molecular entities. Conversion of these compounds to cations leads to structural rearrangement. The thus obtained molecules will be used to build structurally defined germanium clusters. Similarly to the mentioned nanowires, these clusters, which can be further functionalized, are of high interest as materials for various applications of nano-technology.