The aim of this project is the synthesis and structural characterization of nitroso derivatives of the heavier group IV elements, R3E-NO (E = Si, Ge, Sn). The substituents R are varied in size, electronegativity and molecular hardness in order to study these effects on the bonding situation around the central atom. Besides the synthesis a major part of the project should involve the structural characterization by gas phase electron diffraction, which seems to be the method of choice for this new class of molecules. However, it is also intended to explore the further chemistry of these compounds. In particular, reactions with compounds bearing Pi-systems like alkenes, disilenes, iminosilanes etc. seem to be promising regarding the build-up of new (ring) systems. After isolation and structural characterization of the nitroso compounds, CVD related applications will be the focus of the work. Especially the synthesis of new Si-N-O and Si-O-N-C based materials seems to be an exciting topic of research. Nevertheless, even for CVD related processes the knowledge about the gas-phase structure of nitroso compounds is essential for a prediction of the properties of the synthesized materials.