Preparation of Sn-, Ge-, and Si-heterocycles from zirconacycles

Stannacycles such as stannacyclopentanes, stannacyclopentenes and stanacycl openeadienes were prepared from the corresponding zirconacycles. The effect : of addition of CuCl on the reaction of zirconacycles with tin halides is remarkable. In the case of germanium and silicon halides, the remarkable ef fect of CuCl addition was not observed. Symmetrical or unsymmetrical germa- and silacycles were prepared by the reaction of silicon or germanium halid es with dilithio compounds prepared from the corresponding zirconacycles. S everal heterocyclic compounds containing two metalloatoms were also prepare d.