STUDIES OF VACUUM PYROLYSIS OF 3-SILA AND 3-GERMA-3,3'-SPIROBI(6-OXABICYCLO[3.1.0]HEXANES) AND LOW-TEMPERATURE MATRIX STABILIZATION OF MONOMERIC SILICON DIOXIDE FROM THE GAS-PHASE

Vacuum pyrolysis of 3-sila-3,3'-spirobi(6-oxabicyclo[3.1.0]hexanes) le ads to the formation of monomeric silicon dioxide and 1,3-butadienes, whereas under the same conditions 3-germa-3,3'-spirobi(6-oxabicyclo[3. 1.0]hexanes) afford germanium monoxide, the corresponding divinyl ethe rs, and 1,3-butadienes. A multistage mechanism of pyrolytic decomposit ion of the above spirobicyclohexanes was proposed on the basis of expe rimental data and calculations. The different behavior of the silicon and germanium compounds having similar structures can be explained by an increase in the bivalent state stability and by a decrease in the e nergy of the metal-oxygen double bond on the transition from silicon t o germanium.