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.