Novel disilane chemistry: Silyl radical catalyzed cyclo-trimerization of alkynes, synthesis of 1,4-disilacyclohexa-2,5-dienes and silicon hypercoordination studies.

摘要

This dissertation consists of four papers and a research proposal as an extension of current research.; Si2Cl6 and Si(OMe)6 were found to be efficient in cyclo-trimerizing alkynes; into the corresponding aromatic products. A proposed silyl radical pathway is supported by the addition of radical quenchers to the reaction system, by the observation of catalytic trimerization properties of hexachlorodisilane and hexamethyoxydisilane toward alkynes, and by UV-visible irradiation experiment which afforded cyclo-trimerization products.; 1,4-Disilacyclohexa-2,5-dienes can be synthesized either by reacting disilanes bearing multiple dimethylamino groups. A proposed silylene pathway is supported by the identification of the by-products from the reactions, and by trapping an intermediate reaction product after the addition of 1,4-diphenyl-1,3-butadiene to the pentakis(dimethylamino)disilane/diphenylacetylene reaction system.; Disilanes with electron-withdrawing groups react readily with 1,2-quinones and p-quinones to afford disilylated products in the absence of a transition metal catalyst in contrast to earlier reports. A proposed pathway involving the formation of hypercoordinated silicon species was supported by adduct formation reactions between Si2Cl 6 and diamines and DMF, and the reaction between acetamide salts and Si2Cl6, a hexacoordinated silicon complex was synthesized in one of these experiments.; The observations reported in the papers of this thesis are related by the following properties of disilanes: relative weakness of the Si-Si bonds, especially when electron-withdrawing substituents are present on the silicon atoms; relatively easy disproportionation of disilanes bearing multiple dimethylamino to afford silylene species due to the weakness of Si-Si and Si-N bonds; enhanced hypercoordination tendencies of disilanes bearing electron-withdrawing groups.