Isolation and Reactivity of a Digerma Analogue of Vinyllithiums: a Lithium Digermenide

The versatile reactivity
of disilenides, heavier analogues of vinyl
anions, opened the door to novel heavier group 14 structure motifs
with residual functionalities in the periphery around the SiSi
moiety. The corresponding germanium analogue, digermenide Tip2GeGe­(Tip)­Li·dme2 (Tip = 2,4,6-triisopropylphenyl,
dme = 1,2-dimethoxyethane), has now been obtained from the reduction
of Tip2GeCl2 with 3.3 equiv of Li powder and
a catalytic amount of naphthalene in dme at −70 °C. The
lithium digermenide was characterized by NMR spectroscopy, UV/vis
spectroscopy, X-ray diffraction, and DFT calculations. As proof of
principle for its suitability for the nucleophilic transfer of the
GeGe motif, the reaction with chlorosilanes leads to the unsymmetrically
substituted digermenes Tip2GeGe­(Tip)­SiR3.