Abstract
Polycyclic compounds with nitogen, (silicon, carbon) and metallic main group elements like Ge, Sn, As, Sb and Bi forming the skeleton have been synthesized by two different ways. By a first route the components of the compounds are put together by classical salt elimination reactions while by the second procedure a Lewis acidic center in the molecule (Ge) serves as target for an intramolecular attack of a nitogen base. If this nitrogen atom has an trimethylsilyl substituent a trimethylsilyl migration to the electronegative end of the Ge=X bond (X=O, N-SiMe3, S) is observed parallel to the Ge-N bond formation; if the nitorgen atom is substituted by tert-butyl, an intramolecularly N-coordinated Ge=X system is isolated as a crystalline compound.