Differentiating Between Monodentate and Bidentate Carboxylate Ligands Coordinated to Uranyl Ions Using EXAFS

摘要

We have investigated the U L_m-edge EXAFS of two carboxylato uranyl complexes of known structure to explore the possibilty of differentiating between monodentate and bidentate coordinated carboxylate ions. The interpretation of EXAFS results from uranyl complexes with carboxylate ions based solely on axial and equatorial bond lengths can be inconclusive; information from further-distant shells is often needed. Multiple scattering (MS) pathways along the O=U=O unit and in coordinating chelating or monodentate carboxylate groups can make substantial contributions to the EXAFS. Therefore, MS pathways were calculated using FEFF6 [1] and considered in the data analysis. EXAFS results are compared to XRD data reported in the literature.