酸性磷(膦)稀土萃取剂的空间结构和电子结构特征

Quantum Chemical Calculation of the Structures and Electronic Properties of Phosphonate Ester as Rare Earth Extractants

用分子力学（Ｍｏｌｅｃｕｌａｒｄｙｎａｍｉｃｓ）、分子动力学及量子化学方法研究了系列酸性磷（膦）萃取剂的空间结构和电子结构。结果表明，它们存在较为明显的特征。空间结构方面，所有Ｐ原子均采取ｓｐ３杂化，萃取剂的空间结构取决于取代基之间的核排斥作用，在有两个２乙基己基的萃取剂中，其中一个取代基呈链状结构，而另一个呈弯曲结构。在电子结构方面，磷酰氧原子的负电荷随化合物中Ｏ原子数目的减少逐渐增多；羟基上Ｏ原子的负电荷和Ｈ原子的正电荷随着化合物中Ｏ原子数目的减少逐渐减小。各萃取剂电子占据前线轨道之间的能级相差较小，ＨＯＭＯ轨道和ＬＵＭＯ轨道的能级随体系中Ｏ原子数的减少而升高。这些结果为进一步研究萃取剂结构—性能关系和发展分子设计提供了有用的信息和数据。

Molecular mechanics, molecular dynamics and semi-empirical quantum chemical method have been used to study the geometric and electronic structures of six phosphonate esters as rare earth extractants. The results show that the phosphorus atom exhibits sp3 hybridization. The structures of the extractants are determined by the repulsion of the hydrocarbon groups. In the extractants that have two 2-ethyl-hexyl groups, one 2-ethyl-hexyl extends straight, another extends twistily. When the number of oxygen atom decreases, the negative charge of the phosphoryl oxygen atom increases; but the negative charge of oxygen atom and the positive charge of hydrogen of the hydroxyl group decreases; and the energies of HOMO and LUMO orbitals increase. The energies of the occupied frontier orbitals are close to each other.