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

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.