Synthesis of Tris(pentafluoroethyl)germanes.

The synthesis of tris(pentafluoroethyl)germanium derivatives is described. The reaction of germanium tetrachloride with three equivalents of the pentafluoroethylation reagent LiC F does not lead selectively to the formation of tris(pentafluoroethyl)chlorogermane, (C F ) GeCl. Here the introduction of a diethylamino function as a protecting group was beneficial. Thus, treatment of Cl GeNEt with LiC F smoothly afforded (C F ) GeNEt . The replacement of the amino substituent by halides was accomplished by reaction with HBr or HCl on a multigram scale. The combination of (C F ) GeCl with Ag CO gave rise to the formation of the digermoxane [(C F ) Ge] O. An obtuse Ge-O-Ge angle of 150.2(1)° was determined by X-ray diffraction. Attempted hydrolysis of the digermoxane leads to an equilibrium mixture of the precursor, (C F ) GeOH, and water.