Synthesis of Genuine Germenyl Lithiums and the First Persistent Germenyl Radicals

The first isolated genuine germenyl lithiums (R(3)Si)(1‐Ad)C=Ge(SiMetBu(2))(Li⋅2 L) (R(3)Si=tBu(2)MeSi, L=THF (1 a), or L=12‐crown‐4 (1 b) and R(3)Si=tBuMe(2)Si, L=THF (2 a), or L=12‐crown‐4 (2 b)), were synthesized by reaction of the corresponding acyl germanes 3 and 4, respectively, with tBu(2)MeSiLi in THF at 70 °C. The novel 1 a and 2 b were characterized by NMR and UV/Vis spectroscopy, and also by X‐ray crystallography (r(C=Ge)=1.865 Å for 1 a and 1.877 Å for 2 b). Nucleophilic addition reaction of 1 a with MeI and a C−H insertion reactions to the C=Ge bond of 1 a, 2 a and 2 b, are reported. Oxidation of 1 a and 2 b (toluene, 230 K) produces the first persistent germenyl radicals (R(3)Si)(1‐Ad)C=Ge⋅‐(SiMetBu(2)) (R(3)Si=tBu(2)MeSi (13 a), R(3)Si=tBuMe(2)Si (13 b)), which were characterized by EPR spectroscopy (t (1/2)≈30 min at 230 K, g=2.029, a (av)((73)Ge) is 55.0G for 13 a and 60.2G for 13 b). The experimental EPR parameters and DFT calculations indicate that 13 a and 13 b have a strongly bent structure at Ge (calc. ∡(C=Ge−Si)=136.7° (13 a), 135.9° (13 b)), and that the unpaired electron has a substantial s‐character.