Coordination dynamics of heterodonor ligands with lanthanide and actinide by time dependent DXAFS

Yaita, Tsuyoshi; Kobayashi, Toru ; Matsumura, Daiju   ; Suzuki, Shinichi

To improve fundamental theories regarding molecular design for f-elements extractant, coordination dynamics of the unsymmetrical N,O-mixed heterodonor ligand, N-octyl-N-tolyl-1,10-phenanthroline-2-carboxamide(PTA), with lanthanide and actinide were investigated by time dependent energy dispersive X-ray absorption fine structure (TD-DXAFS) method. In addition to PTA, symmetrical 1,10-phenanthroline (Phen) was used as comparison. The time dependent radial structure function of DXAFS showed that PTA has slightly delayed on achieving equilibrium of coordination structure with lanthanide and chemical shift value, compared to symmetrical Phen. The shift direction of absorption edge DXAFS spectrum for the tetravalent uranium was positive while that for the trivalent europium was negative. This result suggests that uranium formed covalent bond with N donor atoms, and lanthanide formed ionic bond. This is because chemical shift direction depends on electron density of each ion. In this presentation, stepwise changes of coordination structure and electronic structure of the metal-ligand complexes during interaction will be discussed in detail from the EXAFAS parameters.