Low‐Valent Germanylidene Anions: Efficient Single‐Site Nucleophiles for Activation of Small Molecules

Rare mononuclear and helical chain low‐valent germanylidene anions supported by cyclic (alkyl)(amino)carbene and hypermetallyl ligands were synthesised by stepwise reduction from corresponding germylene precursors via stable and isolable germanium radicals. The electronic structures of the anions can be described with ylidene and ylidone resonance forms with the Ge−C π‐electrons capable of binding even weak electrophiles. The germanylidene anions reacted with CO2 to give μ‐CO2‐κC:κO complexes, a rare coordination mode for low‐valent germanium and inaccessible for the related neutral germylones. These results implicate low‐valent germanylidene anions as efficient single‐site nucleophiles for activation of small molecules. Stepwise reduction of germylenes via stable and isolable germanium radicals yields germanylidene anions supported by cyclic (alkyl)(amino)carbene and hypermetallyl ligands. The anions contain a highly electron‐rich germanium centre with significant ylidone character and are efficient single‐site nucleophiles that react even with weak electrophiles.