The Interaction of Crown Ethers with B-Diketonate Complexes of f-elements

The interaction of UOz z plusEu3plus, La3plus and Th4pluscomplexes of TTA with several crown ethers have been investigated in benzene and chloroform. The thermodynamic (AG, AH, AS) parameters were measured by extraction and by titration calorimetry. The hydration of the complexes were determined by Karl Fischer and fluorescence techniques. NMR (H-l and C-13) spectra were used to further clarify the nature of the complexes. These spectra indicated that the metal ion more often does not interact equally with all the ether oxygens and the “fit” of the cation to the CE cavity is not significant. The binding to the simple crowns by Ln(TTA)3and UOz(TTA)2follows the CE basicity sequence but with DChl8C6 and DB18C6, steric effects become more important. Such effects are important for Th(TTA)4interactions even in the interactions with the simple crown ether.