(KN3)n(n=1~5)团簇结构与性质的密度泛函理论研究

利用密度泛函理论B3LYP方法, 在6-311G*基组水平上对(KN3)n(n=1~5)团簇各种可能的结构进行了几何结构优化, 预测了各团簇的最稳定结构. 并对最稳定结构的振动特性、成键特性、电荷分布和稳定性性质进行了分析研究. 结果表明, 叠氮化合物中叠氮基以直线型存在, KN3团簇最稳定结构为直线型, (KN3)n(n=2~3)团簇最稳定结构为环形结构, (KN3)n(n=4~5)团簇最稳定结构是由(KN3)2团簇最稳定结构形成的平面和空间结构. N-N 键键长在0.1156~0.1196 nm之间, N-K键键长在0.2357~0.2927 nm之间; 叠氮基中间的N原子显示正电性, 两端的N原子显示负电性, 且与K原子直接作用的N原子负电性更强, 金属K原子与N原子之间形成离子键. (KN3)n(n=1~5)团簇最稳定结构的IR光谱最强振动峰均位于2180~2230 cm-1, 振动模式为叠氮基中N-N键的反对称伸缩振动. 稳定性分析显示, (KN3)3团簇具有相对较高的动力学稳定性.

Density functional theory study on the structure and properties of (KN3)n(n=1~5) clusters

Possible geometrical structures and relative stability of (KN3)n(n=1~5) clusters are studied by using the hybrid density functional theory (B3LYP) with 6-311G* basis sets. For the stablest isomers of (KN3)n(n=1~5) clusters, the bond properties, charge distributions, vibrational properties, and stability are analyzed. The calculated results show that azido in azides has linear structure, the most optimized KN3 has linear structure, the most optimized (KN3)n(n=2~3) have plane structure of ring structure, and the most optimized (KN3)n(n=4~5) have the plane or space structures composed by the most optimized KN3 cluster. The bond lengths for the most of the optimized (KN3)n(n=1~5) clusters are about 0.1156~0.1196 nm for N-N and 0.2357~0.2868 nm for N-K. The middle N atoms of azido show positive, the N atoms at both ends of azido show negative, and the N atoms effected with K atoms directly show more negative. There is a ionic bond between the K atoms and N atoms. The whole strongest vibrational peak of the IR spectra of the most optimized (KN3)n(n=1~5) clusters lies in 2180~2230 cm-1, and the vibrational mode is anti-symmetric stretching vibration of N-N bonds in azido. Stability analysis shows that (KN3)3 cluster is more stable than other clusters.