High‐Pressure Synthesis of Antimony Nitride $Sb_3N_5$ and Polynitride $Sb_2N_8$ Featuring Single‐Bonded $N_8^{10−}$ Chains

High-pressure high-temperature synthesis in laser-heated diamond anvil cells provides a direct pathway tostabilize polymeric and oligomeric nitrogen units, often inaccessible under ambient conditions due to the stability of theN2 molecule. Here we report the high-pressure reactivity of antimony with molecular nitrogen, leading to the discoveryof two distinct binary nitrides. At megabar pressures, we synthesized and structurally characterized mP20-Sb 2 (N8 ), thefirst pnictogen oligonitride containing unprecedented twisted single-bonded (N8 ) 10− chains. The compound was identifiedby single-crystal x-ray microdiffraction and Raman spectroscopy, supported by density functional theory calculations. Atlower pressures of ∼ 50 GPa, we observed the formation of oC32-Sb 3 N5 , complementing recent reports of this phase bythe studies of its compressional behavior and stability field. These results significantly expand the interpnictogen chemistryand demonstrate the ability of antimony to stabilize unusual extended nitrogen fragments at high pressures