Four new silicon compounds, dimethoxysilanediyl bis(5H-octafluoropentanoate), (CH3O)2Si[OCO(CF2)4H]2, dimethoxysilanediyl bis(7H-dodecafluoroheptanoate), (CH3O)2Si[OCO(CF2)6H]2, dimethoxysilanediyl bis(9H-hexadecafluorononanoate), (CH3O)2Si[OCO(CF2)8H]2, and dimethoxysilanediyl bis(pentadecafluorooctanoate), (CH3O)2Si[OCO(CF2)6CF3]2, were prepared by the reaction of dichlorodimethoxysilane with sodium