气相和水溶液中铀酰配合物UO2L 2-n*an (L=F-, CO2-3, NO-3; n=0-6, a=1, 2)的结构和振动光谱

通过对铀采用相对赝势基组, 其它原子使用6-31+G(d)基组, 应用密度泛函理论(DFT)以及B3LYP方法对UO2+2离子与F-、CO2-3和NO-3的各配位结构进行优化和频率计算. 计算考虑了气相和水溶剂化两种状态, 其中溶剂化模型采用连续导体介质理论模型(CPCM). 计算结果显示配体的配位数与O=U=O对称伸缩振动频率存在线性关系. 配体在气相和水溶液中存在的关系基本符合通式: νs=-Agasn+983和νs=-Aaqn+821(Agas 和Aaq为常数, 表示每增加一个配体振动频率的变化值; n为配体配位数). 其中F-对应Agas=53 cm-1, Aaq=11 cm-1; CO2-3对应Agas=85 cm-1, Aaq=19 cm-1; NO-3对应Agas=48 cm-1, Aaq=-10 cm-1. 并且Aaq值与实验值一致.

Structures and Vibrational Frequencies of Gas Phase and Solvated Uranyl Complexes UO2L 2-n*an (L=F-, CO2-3, NO-3; n=0-6, a=1, 2)

The geometries and IR frequencies of uranyl complexes were calculated by B3LYP method in density
functional theory (DFT) using the relative effective core potential (RECP) on uraniumand 6-31+G(d) basis set on other elements. Both gaseous and aqueous phases were considered and conductor-like polarized continuum model(CPCM) was used to consider the solvation effect of water. Ligands investigated in the present paper were F-, CO2-3, and NO-3. A linear correlation between the frequency of the O=U=O symmetrical stretching vibration and the number (n) of ligands was established for the above-mentioned ligands according to the following two equations: νs=-Agasn+983 and νs=-Aaqn+821, where Agas and Aaq are characteristic coefficients that represent the shift in vibrational frequency for the addition of each ligand to the uranyl center. Results obtained for F- fit the equations with Agas=53 cm-1 and Aaq=11 cm-1; CO2-3 with Agas=85 cm-1 and Aaq=19 cm-1; NO-3 with Agas=48 cm-1 and Aaq=-10 cm-1. The value of Aaq was found to correspond to the experimental results.