Coordination of Trivalent Lanthanides with Bismalonamide Ligands: Implications for Liquid-Liquid Extraction

摘要

The complexation of the bismalonamide ligand 2,2'-(1,2-phenylenebis(methylene))(,,,-tetraethylmalonamide) (L), bearing two -alkylated ,,,-tetraethylmalonamide groups onto -xylylene (CH(CH)) platform, with trivalent lanthanides was investigated both in solid- and solution states. The crystal structures [Nd(NO)L]·(CHCN) (), [Nd(NO)L]·[Nd(NO)5]·(CHCN) (), Ce(NO)L () and [NdL]·(ClO)·CHOH () were analyzed by single-crystal X-ray diffraction. The -bismalonamide (L) is tetradentate in the structures , and and bidentate in only. It was found that the structures and are composed of dimeric species. According to electrospray ionization - mass spectrometry the dimers are prevailing in acetonitrile solutions. The polydentate coordination of the -bismalonamide (L) with trivalent lanthanides suggests that an entropy effect favors liquid-liquid extraction of the metal ions with this type of ligands.