An isolable germa-isonitrile featuring a terminal nitrogen-germanium triple bond

Isonitriles (R–N ≡ C), first discovered by Lieke in 1859, have been ubiquitously leveraged in organic and organometallic synthesis. By contrast, their heavier group 14 analogues (R–N ≡ E, E = Si, Ge, Sn, Pb), known as tetrela-isonitriles, remained elusive due to their high reactivity, and have been detected only spectroscopically under cryogenic or gas-phase conditions. Here, we report the synthesis and characterization of a germa-isonitrile (Ar–N ≡ Ge) stabilized by a bulky aryl ligand. The compound features an almost linear terminal N ≡ Ge triple bond with a distance of 1.6395(19) Å, hitherto the shortest reported N–Ge bond, as evidenced by X-ray crystallographic and solid-state ¹⁵N nuclear magnetic resonance spectroscopic characterizations coupled to computational studies. The highly polarized N ≡ Ge moiety exhibits versatile reactivity toward organic substrates and transition metal precursors, demonstrating its potential in synthetic chemistry.