Aromatic hexazine [N₆]⁴⁻ anion featured in the complex structure of the high-pressure potassium nitrogen compound K₉N₅₆

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Laniel, Dominique ; Trybel, Florian ; Yin, Yuqing ; Fedotenko, Timofey ; Khandarkhaeva, Saiana ; Aslandukov, Andrii ; Aprilis, Georgios ; Abrikosov, Alexei I. ; Bin Masood, Talha ; Giacobbe, Carlotta ; Bright, Eleanor Lawrence ; Glazyrin, Konstantin ; Hanfland, Michael ; Wright, Jonathan ; Hotz, Ingrid ; Abrikosov, Igor A. ; Dubrovinsky, Leonid ; Dubrovinskaia, Natalia:
Aromatic hexazine [N₆]⁴⁻ anion featured in the complex structure of the high-pressure potassium nitrogen compound K₉N₅₆.
In: Nature Chemistry. Bd. 15 (2023) . - S. 641-646.
ISSN 1755-4349
DOI: https://doi.org/10.1038/s41557-023-01148-7

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Abstract

The recent high-pressure synthesis of pentazolates and the subsequent stabilization of the aromatic [N5]− anion at atmospheric pressure have had an immense impact on nitrogen chemistry. Other aromatic nitrogen species have also been actively sought, including the hexaazabenzene N6 ring. Although a variety of configurations and geometries have been proposed based on ab initio calculations, one that stands out as a likely candidate is the aromatic hexazine anion [N6]4−. Here we present the synthesis of this species, realized in the high-pressure potassium nitrogen compound K9N56 formed at high pressures (46 and 61 GPa) and high temperature (estimated to be above 2,000 K) by direct reaction between nitrogen and KN3 in a laser-heated diamond anvil cell. The complex structure of K9N56—composed of 520 atoms per unit cell—was solved based on synchrotron single-crystal X-ray diffraction and corroborated by density functional theory calculations. The observed hexazine anion [N6]4− is planar and proposed to be aromatic.