An isolable germylyne radical with a one-coordinate germanium atom

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Radical Chemistry

Background:

• Carbynes, featuring a monovalent carbon atom with three non-bonding valence electrons, are crucial intermediates in organic synthesis.
• Isolating free carbene analogues of group 14 elements (E) in condensed phases has been challenging due to their inherent high reactivity.

Purpose of the Study:

• To report the successful isolation and characterization of a stable germylyne radical.
• To investigate the electronic structure and reactivity of this novel germylyne species.

Main Methods:

• Synthesis utilizing a sterically demanding hydrindacene ligand to stabilize the reactive germylyne.
• Single-crystal X-ray diffraction for structural determination.
• Electron paramagnetic resonance (EPR) spectroscopy and theoretical calculations for electronic structure analysis.

Main Results:

• Isolation and characterization of a crystalline germylyne radical with a one-coordinate germanium atom.
• EPR spectroscopy and computational studies confirmed a doublet ground state.
• The germanium atom's non-bonding electrons populate the highest occupied molecular orbital (HOMO-3) and singly occupied molecular orbital (SOMO).

Conclusions:

• The steric bulk of the hydrindacene ligand enables the isolation of a highly reactive germylyne radical.
• The characterized germylyne radical exhibits unique electronic properties, including a doublet ground state.
• This work opens new avenues for exploring the chemistry and applications of low-coordinate group 14 species.