Synthesis of Potassium Oligosilanides in Benzene

Despite the initial assumption that the reaction of methylated oligosilanes, like (Me3Si)4Si, with tBuOK to afford potassium oligosilanides requires ethereal solvents or crown ether, we found that the reaction also proceeds in benzene. However, forced reaction conditions and long reaction times are required to obtain complete conversion. The related reaction of the phenyl‐substituted oligosilane (PhMe2Si)3SiMe proceeds much faster and suggests interaction of the substrate's phenyl groups with the potassium ions, facilitating the reaction. Attempts to accelerate the reaction of methylated oligosilanes by using large excess amounts of tBuOK are successful. However, the silanides formed in this reaction co‐crystallize with tBuOK. The reaction of methylated oligosilanes with potassium tert‐butoxide in benzene gives base‐free oligosilanides but requires higher temperature and long reaction times. Replacing some of the methyl groups by phenyl significantly accelerates the reaction. We assume this is caused by interaction between potassium ions and phenyl substituents.