Synthesis and Redox Behavior of Si–Si Dimeric 9-Methylsilafluorene

Abstract

Lithium-halogen exchange on 2,2’-dibromo-1,1’-biphenyl followed by salt metathesis with 1,1,2,2-tetrachloro-1,2-dimethyldisilane produced the Si–Si linked dimeric 9-methylsilafluorene (1) in 45% yield. Compound 1 was characterized in the solid state via single crystal X-ray diffraction, which revealed a highly symmetric structure. The redox behavior of 1 was studied experimentally via cyclic voltammetry, where irreversible oxidation and reduction features were observed. Density functional theory was used to further study the electronic structure of 1 as well as its reduced (1•-) and oxidized (1•+) forms. A decrease in bond dissociation energies from the neutral species (+75 kcal mol-1) to the reduced species (+43 kcal mol-1) supports Si–Si bond homolysis upon reduction, which is consistent with our observed electrochemical irreversibility.