Reactivity of dianionic hexacoordinate germanium complexes toward organometallic reagents. A new route to organogermanes

Article abstract of DOI:10.1021/om00051a049

Lithium and potassium tris(benzene-1,2-diolato)germanates (2a and 2b, respectively) and potassium tris(butane-2,3-diolato)germanate (3) are easily prepared from GeO₂ in quantitative yields. They are very reactive toward organometallic reagents, the reactivity depending on the ligands on the germanium. Complexes 2 react with an excess of Grignard reagent to give the corresponding tetraorganogermanes R₄Ge while the less reactive complex 3 leads to the functional triorganogermanes R₃GeX. Tetraorganogermanes can also be prepared from complex 2b by reaction with organic bromides in the presence of Mg (Barbier reaction). The influence of Cp₂TiCl₂ and MgBr₂ on the reactivity of Grignard reagents with these complexes was also investigated: in both cases formation of triorganogermanes was favored.