Synthesis and Properties of Tripodal Phosphine Oxide Ligand With Phthalimide Pendants

ABSTRACT Tris{2''‐[3'‐(1,3‐dioxoisoindol‐2‐yl)propoxy]phenyl}phosphine oxide ( L ) has been synthesized. The complexes of ligand L with U(VI), Th(IV) have been isolated and studied in solid state and chloroform solution by elemental analysis, IR, Raman, NMR spectra, and x‐ray diffraction. Extraction properties of ligand L have been studied by the example of recovery of micro amounts of U(VI), Th(IV), and Ln(III) from 3 M NH 4 NO 3 solutions into chloroform. In crystalline complex [UO 2 L (H 2 O)(NO 3 ) 2 ], the ligand is coordinated by means of phosphoryl group, while one of the C═O groups forms hydrogen bond with coordinated water molecule. In the solid complex [Th 2 L 3 (H 2 O) 5 (NO 3 ) 8 ], phosphoryl groups of the ligands, nitrate anions, water molecules are coordinated, C═O groups form H‐bonds. The results of the solutions study have been compared with extraction data. In solution, the complexes are formed due to coordination of phosphoryl group and stabilized owing to hydrogen bonds of carbonyl groups. This stabilization improves extraction ability. According to extraction study, compound L exhibits significantly higher extraction ability toward U(VI) and Th(IV) compared to phosphine oxide Ph 3 P(O), (BuO) 3 PO, and Ph 2 P(O)CH 2 CONBu 2 . The UV–vis spectra showed that complexation of ligand L with UO 2 and Th nitrates does not affect considerably the character of absorption spectra.