טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentIlya Ruderfer
SubjectThe Chemistry and Reactive Intermediates in Reactions of
Compounds with Mercury-Silicon Bonds
DepartmentDepartment of Chemistry
Supervisor ? 18? Apeloig Yitzhak


Abstract

Silicon chemistry has grown tremendously over the last 2 decades due to its many practical applications and the inherent scientific interest in this higher congener of carbon. However, despite significant effort relatively little is still known, about the fundamental properties and the reaction mechanisms of organosilicon compounds. This research focuses on two main topics: (1) generation and structural assignment of new types of silyl radicals. (2) synthesis and structural characterization of novel silyllithium and dimetallic silicon compounds.

Following recent synthesis in our group of the trimercury silicon compound, (t-BuHgR2Si)2Hg, R = i-Pr3Si (1), a novel trimercury silicon compound with bulkier R = t-Bu2MeSi (2), was synthesized. Photolysis of 1 and 2 produces novel mercury-substituted silyl radicals of the type R’HgR2Si·, that were characterized by EPR spectroscopy and by trapping experiments. The first known radical centered on a Si atom which is part of a silyllithium dimer, HR2SiLiR2LiSi·, R = t-Bu2MeSi, was generated by lithiation of 2 and characterized by EPR spectroscopy.

Lithiation of 1 produced the geminal dilithium silicon compound, R2SiLi2, R = i-Pr3Si, and the first known silyllithium compound exhibiting p-complexation to an aromatic molecule (h6-toluene LiR2Si)2Hg, R = i-Pr3Si (3) and its molecular structure was determined by X-ray crystallography. Theoretical density functional calculations showed that silyllithium compounds are expected to have an aggregated form in aromatic solvents. Nevertheless, when steric effects hinder aggregation of silyllithium compounds, complexes with aromatic molecules are expected, as indeed found for 3.