Silanortricyclenes and Silaadamantanes

By reaction of Si-compounds composed of four to ten silicon atoms with appropriate nitrogen, phosphorus, arsenic, oxygen and sulfur derivatives novel cage-like molecules with extended silicon skeletons have been synthesized. The arrangements of the atoms in these molecules have been determined by diffraction of X-rays. The starting point for the project was the problem of synthesizing cage-like molecules containing silicon atoms and the investigation of their properties. Of special interest was the question whether or not cages composed of three- membered silicon rings can be prepared. The synthetic principles discovered in the project will facilitate and make possible the synthesis of further cage-like molecules with silicon skeletons.

In the project, cage-like compounds with backbones composed of the elements silicon, phosphorus and arsenic were synthesized. The cages are composed of three ore more fused rings of variable size (six-, five-, four- and threemembered rings) that contain SiSi, PP, SiP or SiAs bonds. Methods for synthesizing thes cages were developed, as well as methods for introducing functional groups. Functionalization allowed the synthesis of species composed of two cages interconnected by a spacer, a first step towards polymers. The properties of the cages synthesized in the project were investigated with varoius physical methods such as Raman spectroscopy and NMR spectroscopy, and also with quantum chemical ab initio calculations.