磷酸三丁酯和磷酸二丁酯与Pu(Ⅳ)配合物的密度泛函研究

Density Functional Theoretical Analysis of Complexes of Tributylphosphate and Dibutylphosphate of Pu(Ⅳ)

采用B3LYP密度泛函方法,Pu(Ⅳ)和其他原子分别采用相对论有效原子实势(RECP)和6-311g(d,p)全电子基组,研究了Pu(NO3)4TBP2和Pu(NO3)2DBP2的几何结构、热力学参数及紫外可见光谱。几何结构计算结果表明,由于配体空间位阻的影响,Pu与DBP的键长更短,自然布居分析(NPA)结果也表明,Pu与DBP之间的电荷转移更多,因此二者之间相互作用更强。热力学分析显示,Pu(NO3)4TBP2与HDBP发生配体交换的反应自由能为-178.9kJ/mol,说明DBP与Pu之间的相互作用更强。Pu(NO3)4TBP2的紫外吸收光谱主要来源于硝酸根到Pu的f轨道的跃迁,TBP贡献不大;而Pu(NO3)2DBP2的跃迁同时来源于硝酸根和DBP到Pu的f轨道的配体-金属电荷转移跃迁(LMCT)。

The geometry, thermodynamic selectivity and UV-vis spectra of Pu（NO3）4TBP2 and Pu（NO3）2DBP2 in the gas phase were investigated by using B3LYP density functional theory method with the RECP basis for Pu and 6-311 g（d,p） basis for other atoms. The structure optimization results show the bond length between Pu and DBP is shorter than the length between Pu and TBP for the steric hinder of the ligands, and NPA charge analysis shows more electron trasnfer between DBP and Pu ion indicating the stronger coordination ability of DBP. The free energy of ligand exchange between Pu（NO3）4TBP2 and HDBP was -178.9 kJ/mol, indicating the higher coordination affinity between DBP and Pu. The UV- vis absorption spectra of Pu（NOa）4 TBP2 in the gas phase were pmainly from nitrate to f orbital of Pu, TBP ligand made few contribution, yet the absorption spectrum of Pu（NO3）2DBP2 were both from nitrate to f orbital of Pu and the ligand-to-metal charge transfer between DBP and Pu.