Al(N_3)_3和P(N_3)_3结构与性质的理论研究  

A theoretical study of the structures and properties of Al(N_3)_3 and P(N_3)_3

作　　者：朱乾华[1] 黄辉胜[1] 胡武洪[1] 吴兴发[1] 徐建华[1] 

机构地区：[1]长江师范学院化学化工学院,重庆408100

出　　处：《原子与分子物理学报》2013年第3期350-354,共5页Journal of Atomic and Molecular Physics

基　　金：重庆市自然科学基金(cstc2011jjA50013);重庆市教委科技计划项目(KJ111310)

摘　　要：在B3LYP/6-311++G(3df)理论水平,对二元叠氮化合物Al(N3)3和P(N3)3进行密度泛函理论计算研究,获得其稳定分子的几何构型、电子结构、红外光谱以及稳定性.研究结果表明,P(N3)3分子中的磷原子拥有一对孤对电子,给予临近氮原子(Nα)上的孤对电子较大斥力,从而使其表现出三角锥形结构特征,而Al(N3)3表现为平面三角形结构特征.自然键轨道分析表明,Al-Nα和P-Nα键本质上均属于共价键.与叠氮自由基相比较而言,Al(N3)3和P(N3)3的每个叠氮基内部的总成键度显著增大,从而导致N3基的振动频率发生明显蓝移.前线分子轨道能级差和叠氮自由基键离解能的计算结果均表明Al(N3)3比P(N3)3更稳定.The molecular geometries, electronic structures, infrared spectra and stabilities ot binary az- ides Al（N3）3 and P（N3）3 were studied at the B3LYP/6-311＋＋G（3df） level of theory. The obtained results show that Al（N3）3 represents a planar triangular structural feature, whereas P（N3）3 has a trian- gular pyramid structure. These molecular configurations can be easily elucidated by the principle of va- lence shell electron pair repulsion （VSEPR）. Because there are lone-pair electrons on the phosphorus at- om, and it delivers large repulsion to the lone-pair electrons on the adjacent nitrogen atoms, the molecu- lar structure of P（N3）3 is similar to that of NHa. Detailed natural bond orbital （NBO） analyses indicate that there are A1--N. and P--N3 bonding orbitals. Thus, the interactions between the P/A1 atom and the azide group are covalent in nature. In addition, the total bond order of every azide group of Al（N3）3 and P（N3）3 is much stronger than that of the isolated N3 radical. And these results in the vibrational fre- quency of azide group of the two binary azides shifts to the higher wave number compared with that of the isolated N3 radical. Finally, the calculated energy gap and bond dissociation energy for removal of the azide group predict that Al（N3）3 is more stable than P（N3）3.

关 键 词：二元叠氮化合物 密度泛函理论 电子结构 红外光谱 稳定性 

分 类 号：O641[理学—物理化学]