6-(tetrazol-5-yl)-2,2′-bipyridine

• Verfasst von: Kratsch, Jochen [VerfasserIn]
• Verfasst von: Beele, Björn B. [VerfasserIn]
• Verfasst von: Koke, Carsten [VerfasserIn]
• Verfasst von: Denecke, Melissa A. [VerfasserIn]
• Verfasst von: Geist, Andreas [VerfasserIn]
• Verfasst von: Panak, Petra [VerfasserIn]
• Verfasst von: Roesky, Peter W. [VerfasserIn]
• Titel: 6-(tetrazol-5-yl)-2,2′-bipyridine
• Titelzusatz: a highly selective ligand for the separation of lanthanides(III) and actinides(III)
• Verf.angabe: Jochen Kratsch, Björn B. Beele, Carsten Koke, Melissa A. Denecke, Andreas Geist, Petra J. Panak, and Peter W. Roesky
• E-Jahr: 2014
• Jahr: [2014]
• Umfang: 10 S.
• Illustrationen: Illustrationen
• Fussnoten: Gesehen am 10.09.2020
• Titel Quelle: Enthalten in: Inorganic chemistry
• Ort Quelle: Washington, DC : American Chemical Society, 1962
• Jahr Quelle: 2014
• Band/Heft Quelle: 53(2014), 17, Seite 8949-8958
• ISSN Quelle: 1520-510X
• DOI: doi:10.1021/ic5007549
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1729863361

Abstract

The coordination structure in the solid state and solution complexation behavior of 6-(tetrazol-5-yl)-2,2′-bipyridine (HN4bipy) with samarium(III) was investigated as a model system for actinide(III)/lanthanide(III) separations. Two different solid 1:2 complexes, [Sm(N4bipy)2(OH)(H2O)2] (1) and [Sm(N4bipy)2(HCOO)(H2O)2] (2), were obtained from the reaction of samarium(III) nitrate with HN4bipy in isopropyl alcohol, resuspension in N,N-dimethylformamide (DMF), and slow crystallization. The formate anion coordinated to samarium in 2 is formed by decomposition of DMF to formic acid and dimethylamine. Time-resolved laser fluorescence spectroscopy (TRLFS) studies were performed with curium(III) and europium(III) by using HN4bipy as the ligand. Curium(III) is observed to form 1:2 and 1:3 complexes with increasing HN4bipy concentration; for europium(III), formation of 1:1 and 1:3 complexes is observed. Although the solid-state samarium complexes were confirmed as 1:2 species the 1:2 europium(III) solution complex in ethanol was not identified with TRLFS. The determined conditional stability constant for the 1:3 fully coordinated curium(III) complex species is more than 2 orders of magnitude higher than that for europium(III) (log β3[Cm(N4bipy)3] = 13.8 and log β3[Eu(N4bipy)3] = 11.1). The presence of added 2-bromodecanoic acid as a lipophilic anion source reduces the stability constant for formation of the 1:2 and 1:3 curium(III) complexes, but no ternary complexes were observed. The stability constants for the 1:3 metal ion-N4bipy complexes equate to a theoretical separation factor, SFCmIII/EuIII ≈ 500. However, the low solubility of the HN4bipy ligand in nonpolar solvents typically used in actinide-lanthanide liquid-liquid extractions prevents its use as a partitioning extractant until a more lipophilic HN4bipy-type ligand is developed.