State Key Laboratory of Superhard Materials , Jilin University , Changchun 130012 , China.
Inorg Chem. 2019 Feb 18;58(4):2397-2402. doi: 10.1021/acs.inorgchem.8b02889. Epub 2019 Feb 5.
The high-pressure phase diagrams of binary Se-N system have been constructed using the CALYPSO method and first-principles calculations. Four stable compounds ( Cmc2-SeN, P2 /m-SeN, P1̅-SeN, and P1̅-SeN) were identified at high pressures. Various peculiar nitrogen polymerization forms composed of single/double nitrogen-nitrogen bonds were found at the nitrogen-rich condition, such as N-chains in P2/ m-SeN, oligomeric N-chains in P1̅-SeN, and distorted N anion rings in P1̅-SeN. Peculiar nitrogen polymerization forms make these compounds potential high-energy-density materials (HEDMs). Especially, P1̅-SeN has the highest energy density of 4.08 kJ g among the selenium nitrides. The polymerization mechanism of nitrogen in the Se-N system has been explored using the "Lewis-like" two-center-two-electron and three-center-two-electron bonding analysis. Using the nitrogen-rich P1̅-SeN as a prototype, it is found that the famous N distortion in the polymerized nitrogen HEDM can be explained by the interatomic mechanical unbalance which is induced by the three-center two-electron bonding between the metal atom and the two neighboring nitrogen atoms.
采用 CALYPSO 方法和第一性原理计算构建了二元 Se-N 体系的高压相图。在高压下鉴定出了四种稳定的化合物（Cmc2-SeN、P2/m-SeN、P1̅-SeN 和 P1̅-SeN）。在富氮条件下发现了各种由单/双氮-氮键组成的奇特氮聚合形式，如 P2/m-SeN 中的 N 链、P1̅-SeN 中的低聚 N 链和 P1̅-SeN 中的扭曲 N 阴离子环。奇特的氮聚合形式使这些化合物成为潜在的高能量密度材料（HEDMs）。特别是，P1̅-SeN 在硒氮化物中具有最高的能量密度为 4.08 kJ g。使用“类路易斯”的二中心二电子和三中心二电子键合分析，研究了 Se-N 体系中氮的聚合机制。以富氮的 P1̅-SeN 为原型，发现聚合氮 HEDM 中的著名 N 畸变可以通过金属原子和两个相邻氮原子之间的三中心二电子键合引起的原子间机械不平衡来解释。
