乙异羟肟酸与U、Np、Pu配合物的结构和热力学性质的密度泛函理论研究

Density Functional Theoretical Analysis of Complexes of AHA and U, Np and Pu

摘要: 采用密度泛函理论（DFT），在B3LYP/RECP/6-31G(d,p)水平对U(Ⅵ)、U(Ⅳ)、Np(Ⅳ)、Pu(Ⅳ)与乙异羟肟酸（AHA）摩尔比为1∶1和1∶2配合物的结构和热力学参数进行了研究。结构计算发现，M-O键键长随原子序数增加而减短，对配合物进行自然轨道分析（NBO）发现， M和AHA的摩尔比为1∶1的配合物中M-O键是明显的离子键，共价成分很少，在1∶2配合物中M-O键共价成分增加。对配位反应的热力学参数进行计算发现，金属离子与AHA配合物的稳定性依次为Pu(Ⅳ)>Np(Ⅳ)>U(Ⅳ)>U(Ⅵ)，理论计算结果与实验测量得到的稳定常数顺序一致。

Abstract: The geometry and thermodynamic properties of complexes of acetohydroxamic acid（AHA） and U, Np and Pu (1∶1 and 2∶1) were studied by using density functional theory(DFT) at B3LYP/RECP/6-31G(d,p) level. The structure studies show the shortening of M-O bond in complexes along with the increasement of atomic number. NBO analysis show the M-O bonds in the complexes with the mole ratio 1∶1 of M and AHA are representative ionic bonds. However, the M-O bonds in 1∶2 complexes are partial covalent bond components. Thermodynamic property studies reveal the order of the stability of metal AHA complexes is Pu(Ⅳ)>Np(Ⅳ)>U(Ⅳ)>U(Ⅵ). The experiment results are agreement with the theoretical studies.