[3I04-07] Development of Extractant

[3I07] Evaluation of HSAB principle in complexation behavior of uranyl(VI) ion with N₃O₂-, N₂O₃-, N₂O₂S₁-type planar pentadentate Schiff-base ligands

*Tomoyuki Takeyama¹, Satoru Tsushima^1,2, Koichiro Takao¹ (1. Tokyo Institute of Technology, 2. Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR))

Keywords:Uranium, Complexation, coordination chemistry, HSAB principle

Pearson’s Hard and Soft Acids and Bases (HSAB) principle is useful to design organic ligands coordinating with target metal ion despite its empirical nature as a chemical trend. In this principle, UO₂²⁺ is regarded as a hard acid. Therefore, it prefers coordination with relatively hard bases like N and O atoms, while a soft base like S atom is expected not to strongly interact with UO₂²⁺. However, such a trend based on the HSAB principle has not been fully discussed in a comparable coordination structure around UO₂²⁺. In this study, we discuss the effect of HSAB principle for the UO₂²⁺ complexes with N₃O₂-, N₂O₃-, N₂O₂S₁-type planar pentadentate Schiff-base ligands.