Extraction and Complexation Investigation of Palladium(II) by a Nitrilotriacetate-Derived Triamide Ligand

Effective and selective separation and recovery of the fission product palladium from high-level liquid waste are conducive not only to reducing its hazards to the public health and environment but also to alleviate the pressure on the increasing demand for natural palladium. Herein, the Pd²⁺ extraction in an HNO₃ solution with a nitrilotriacetate-derived triamide ligand NTAamide(n-Oct) and the complexation between them were investigated. Using n-octanol as a diluent, NTAamide(n-Oct) demonstrated an excellent selectivity, strong extractability, and high loading capacity for Pd²⁺ extraction. Combined with the results of single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, electrospray ionization-mass spectroscopy, microcalorimetric titration, and slope analysis, the extracted complexes were determined as [PdL₂](NO₃)₂ and [PdL₂][Pd(NO₃)₄] (where L denotes the NTAamide ligand) in 0.10 and 3.0 mol/L HNO₃ solutions, respectively. The extraction model closely depended on the solvation state of Pd²⁺ in the HNO₃ solution. An ion-pair extraction model was proposed and discussed.

New tetradentate N,O-hybrid phenanthroline-derived organophosphorus extractants for the separation and complexation of trivalent actinides and lanthanides

Comparison of the extraction and separation properties between two novel phenanthroline-derived organophosphorus ligands, Et-Ph-BPPhen and Et-Ph-PIPhen.

Unfolding the Extraction and Complexation Behaviors of Trivalent f-Block Elements by a Tetradentate N,O-Hybrid Phenanthroline Derived Phosphine Oxide Ligand

In this work, a tetradentate N,O-hybrid 2,9-bis(diphenylphosphine oxide)-1,10-phenanthroline (Ph₂-BPPhen) ligand was studied for the coextraction of trivalent f-block elements from nitric acid media. The extraction as well as the complexation behaviors of Ph₂-BPPhen with f-block elements were thoroughly investigated using ³¹P and ¹H NMR spectrometry, UV-vis spectrophotometry, single crystal X-ray diffraction, and density functional theoretical (DFT) calculation. Ph₂-BPPhen exhibits remarkably extraction ability for both Am(III) and Eu(III) and more than 99.5% of Am(III) and Eu(III) were extracted from 1.0 M HNO₃ solution. Slope analysis suggests that both 2:1 and 1:1 ligand/metal complexes were probably formed during the extraction. The 1:1 and 2:1 Ln(III) complexes with Ph₂-BPPhen were also identified in CH₃OH solution by NMR spectrometry, and the stability constants were determined via UV-vis spectrophotometry. Structures of the 1:1 Eu(Ph₂-BPPhen)(NO₃)₃ and Am(Ph₂-BPPhen)(NO₃)₃ complexes were further elucidated by single X-ray crystallography and DFT calculations. The higher extractability of Ph₂-BPPhen toward trivalent Am(III) and Eu(III) compared with the previously reported phenanthroline-derived amide and phosphonate ligands was attributed to the stronger affinity of the -P═O(R)₂ group to metal ions. The results from this work indicate that the N,O-hybrid 1,10-phenanthroline derived phosphine oxide ligand can serve as a new and promising candidate for coextraction of trivalent f-block elements in the treatment of nuclear waste.

Ligand rigidity and electronic effect on the complexation of hexavalent plutonyl with three dicarboxylic acids: a combined spectrophotometric and computational study

Both the ligands’ rigidity and electronic structure contribute to the stability and coordination mode of Pu(vi) complexes with three dicarboxylic acids.

Unraveling the complexation mechanism of actinide(iii) and lanthanide(iii) with a new tetradentate phenanthroline-derived phosphonate ligand

The separation and complexation mechanisms of actinide(iii) and lanthanide(iii) with a new phenanthroline-derived phosphonate ligand were studied experimentally and theoretically.