A stable superatomic nitrogen ring crystal under ambient conditions.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42341122.
- Also identified by DOI 10.1126/sciadv.aee5798 and PMC identifier 13292979.
- Licence recorded as CC BY-NC.
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Abstract
The nitrogen ring structure represented by the pentazolate anion (N<sub>5</sub><sup>-</sup>) has received widespread attention due to its potential to form high-energy-density materials. However, the inherent high-energy properties of nitrogen rings make obtaining their stable crystals under ambient conditions a recognized key challenge. Here, we report a stable polynitrogen crystal Li<sub>4</sub>(N<sub>5</sub>)<sub>2</sub> under ambient conditions by first-principles structural and dynamic studies. In its primitive cell, electron transfer from lithium (Li) atoms to N<sub>5</sub> rings occupies their delocalized orbitals, forming anionic N<sub>5</sub><sup>-</sup> in a superatomic state, where Li-N<sub>5</sub> ionic interactions and N<sub>5</sub>-N<sub>5</sub> van der Waals interactions jointly maintain the structural stability. These interactions result in structure anisotropy, where the <i>ab</i>-plane direction is governed by both ionic and covalent interactions, while the <i>c</i>-axis direction is dominated by ionic interactions. Our findings provide an important foundation for the development of high-energy-density materials based on nitrogen rings and for related artificial unit crystallization pathways.