Synthesis of a Germylidenide Anion from the C–C Bond Activation of a Bis(germylene)

The
synthesis of a germylidenide anion by the C–C bond activation
of a bis­(germylene) is described. The reaction of the 2,6-bis­(imino)­phenyl
bromide 1 with nBuLi, followed by reacting
with GeCl2·dioxane, afforded the chlorogermylene [LGeCl]
(2, L = 2,6-(HCNtBu)2C6H3). It was then reacted with 1 equiv of lithium
in tetrahydrofuran (THF), which proceeded through the reduction of
the imine skeleton, along with the C–C bond formation, to afford
the bis­(germylene) [2-(HC-NtBu)-6-(HCNtBu)­C6H3Ge:]2 (3). It was further reacted with 2 equiv of lithium in THF, which proceeded
through the reduction of the germanium­(II) centers, followed by the
homolytic cleavage of the C–C bond, to form the lithium germylidenide
[LGeLi]2 (4). Compounds 2–4 were characterized by NMR spectroscopy and X-ray crystallography.
Their bonding natures were also investigated by theoretical studies.