Isolation and reactivity of an alkyl-substituted germanium(I) radical anion

The isolation of low-valent main group radical species remains a fundamental challenge in synthetic chemistry due to their intrinsic instability. Herein, we report the successful isolation and full characterization of an alkyl-substituted germanium(I) radical anion predominantly stabilized by steric protection with minimal electronic perturbation. This radical anion exhibits thermal stability in both the solid state and in solution at ambient temperature, enabling thorough structural, spectroscopic and reactivity investigations. EPR spectroscopy and DFT calculations consistently verify predominant localization of the unpaired electron at the germanium center. Furthermore, the Ge(I) radical anion presents unique radical reactivity patterns demonstrating by its reactivity investigation. This work represents a rare example of an isolable low-valent group 14 radical species.