An isolable germylyne radical with a one-coordinate germanium atom

Carbynes (R– C : ° ), species that bear a monovalent carbon atom with three non-bonding valence electrons, are important intermediates and potentially useful in organic synthetic chemistry. However, free species of the type R– E : ° of any group 14 element (E) have eluded isolation in the condensed phase due to their high reactivity. Here we report the isolation, characterization and reactivity of a crystalline germylyne radical by using a sterically hindered hydrindacene ligand. The germylyne radical bears an essentially one-coordinate germanium atom as shown by single-crystal X-ray diffraction analysis. Electron paramagnetic resonance spectroscopic studies and theoretical calculations show that the germylyne radical features a doublet ground state, and the three non-bonding valence electrons at the germanium atom contribute to the lone pair of electrons as the highest occupied molecular orbital-3 and one unpaired electron as the singly occupied molecular orbital. Heavy analogues of carbynes of the type R– E : ̇ , where E is a group 14 element, are difficult to isolate in the condensed phase due to their high reactivity. Now, a germylyne radical supported by a sterically hindered hydrindacene ligand has been prepared and structurally characterized. Theoretical calculations show that the spin density mainly resides at the germanium centre.