Synthetic concept of the preparation of a metalloid cluster applying the disproportionation reaction of a subhalide (Ge(I)Br).

The actually most fruitful route for the synthesis of metalloid germanium clusters of the general formulae Ge_nR_m (n > m) applies the disproportionation reaction of Ge(I)halides. The principle mechanism of this synthetic route is summarized in the following scheme:

Within this synthetic strategy two different reaction routes proceed parallel: The disproportionation reaction of the Ge(I) halides, leading at the end to elemental germanium and a germanium halide in higher oxidation state (e.g. Ge(IV)X₄) and the substitution reaction of the halide atoms by bulky ligands proceed parallel. Via the metathesis reaction the intermedially formed metalloid clusters on the way to the element might be kinetically stabilized so that they can be isolated.

This reaction procedure can only work when the disproportionation reaction as well as the metathesis reaction proceed simultaneously as if not, no intermediates might be trapped. Hence, the added ligand source must be reactive enough that the substitution reaction can take place also at low temperature where the disproportionation reaction normally takes place.