5f-Element complexes with a p-tert-butylcalix[4]arene bearing phosphinoyl pendant arms: Separation from rare earths and structural studies

Abstract

a b s t r a c tPhosphinoylated calixarenes feature high coordination ability toward f elements and a great potentiality toward actinide/rare earth separation. Here, we report three characteristic properties of a tetra-phosphinoylated p-tert-butylcalix[4]arene, B 4 bL 4 functionalized with phosphinoyl pendant arms: (i) its coordination ability toward Th(IV) complexation in organic medium, (ii) its ability to separate thorium from yttrium, lanthanum, and europium in three different organic media, and (iii) the X-ray crystal structure of the La complex. Thorium ( ) n ÁxH 2 O (n = 1, x = 1, 1; n = 2, x = 4, 2). Spectroscopic data point to the inner coordination sphere of 1 and 2 containing nitrate ions and water molecules. Molecular modeling of 1 yielded an 8-coordinate species and its coordination polyhedron can be described as a distorted square antiprism while that for 2, a 9-coordinate species, as a distorted tricapped trigonal prism. The extraction study of tetravalent thorium and trivalent rare-earth (Y, La, Eu) ions from acidic nitrate media by B 4 bL 4 in chloroform shows thorium being much more extracted than the rare earths, with selectivity close to 100%. The extraction behavior can be easily modulated by changing the initial conditions (pH, nitrate concentration

Lanthanide phosphine oxide complexes

“…Analysis of the NMR spectra of the 1:1 complex [(15)(67)] (Ln = Eu) indicates that all four PO groups bind to the metal. Weak extraction of lanthanide ions is found for (67) (X = t Bu, Y = OCH 2 P (O)Me 2 , n = 4) in the absence of other reagents [139]. The crystal [140].…”

Synergism as a phenomenon in solvent extraction of 4f-elements with calixarenes

“…16. 88 Ramírez et al 101 have obtained suitable (tetragonal crystals) for X-ray single diffraction with composition [La(S1) (H 2 O) 5 ], in which La(III) ion is not encapsulated into calixarene cavity and is coordinated by all four O(P) atoms. Zhao et al 102 have prepared and characterized two complexes of La 3+ and Eu 3+ ninecoordinated with all four oxygen atoms from phosphinoxide (-CH 2 P(O)Ph 2 ) substituted calix [4]arene as well four oxygen atoms from two bidentate nitrate anions and one oxygen atom from a water molecule ([L$La(OH 2 )(NO 3 ) (2) ]NO 3 and [L$Eu(OH 2 )(NO 3 ) 2 ]NO 3 $CH 3 OH, L ¼ terakis(methylenediphenylphosphinoxide)calix [4]arene) and their crystal structures were determined by X-ray diffraction method showing that the coordination polyhedron is a single-capped square antiprism.…”

Computational Study of Reduction Potentials of Th4+ Compounds and Hydrolysis of ThO2(H2O)n, n = 1, 2, 4

“…As an early actinide element, the structural chemistry of thorium is varied, as documented by experimental − and theoretical studies. − Due to the potential importance of thorium as a future fuel, the solution chemistry has also been investigated. − At pH 7.4 (near physiological pH), thorium salts hydrolyze to form colloidal particles of Th­(OH) 4 . Thorium is a toxic heavy metal, and thorium ions or its hydroxides can react in vivo to form stable complexes with amino acids and proteins. − In addition, because of its most preferred +4 oxidation state, similar ionic radii, and relatively low specific radioactivity, Th 4+ has at times been used as a model for plutonium in coordination and extraction studies. ,,,,− With this research, we seek to describe some of the interactions that must be occurring in thorium containing aqueous solutions.…”