Evidence and consequences of inner sphere hydrogen bonding between ligands in some mixt complexes of actinide and lanthanide

Drastic changes of complexes properties are observed when one hydrogen forming ligand (water, alcohols...) is replaced by an aprotic ligand. In aqueous uranyl (VI) azido complexes there is a red shift of the UV spectra when the last water molecules are replaced by N3- to give UO2(N3)3- and the U-N distance is modified. In europium (III) dialkyldithiophosphate the UV spectra and the metal to sulfur bond are changed by replacement of water by TBP. An important consequence of this phenomena is the solvent extraction. No or small separation of Am (III) from Eu (III) is observed in pure HDEHDTP but addition of TBP leads to high separation coefficients by shortening the Am-S bond