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Issue 2, 2004
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Solvent extraction and lanthanide complexation studies with new terdentate ligands containing two 1,3,5-triazine moieties

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Abstract

The extracting agent 2,6-bis(4,6-di-pivaloylamino-1,3,5-triazin-2-yl)-pyridine (L5) in n-octanol was found, in synergy with 2-bromodecanoic acid, to give DAm/DEu separation factors (SFs) between 2.4 and 3.7 when used to extract the metal ions from 0.02–0.12 M HNO3. Slightly higher SFs (4–6) were obtained in the absence of the synergist when the ligand was used to extract Am(III) and Eu(III) from 0.98 M HNO3. In order to investigate the possible nature of the extracted species crystal structures of L5 and the complex formed between Yb(III) with 2,6-bis(4,6-di-amino-1,3,5-triazin-2-yl)-pyridine (L4) were also determined. The structure of L5 shows 3 methanol solvent molecules all of which form 2 or 3 hydrogen bonds with triazine nitrogen atoms, amide nitrogen or oxygen atoms, or pyridine nitrogen atoms. However, L5 is relatively unstable in metal complexation reactions and loses amide groups to form the parent tetramine L4. The crystal structure of Yb(L4)(NO3)3 shows ytterbium in a 9-coordinate environment being bonded to three donor atoms of the ligand and three bidentate nitrate ions. The solvent extraction properties of L4 and L5 are far inferior to those found for the 2,6-bis-(1,2,4-triazin-3-yl)-pyridines (L1) which have SF values of ca. 140 and theoretical calculations have been made to compare the electronic properties of the ligands. The electronic charge distribution in L4 and L5 is similar to that found in other terdentate ligands such as terpyridine which have equally poor extraction properties and suggests that the unique properties of L1 evolve from the presence of two adjacent nitrogen atoms in the triazine rings.

Graphical abstract: Solvent extraction and lanthanide complexation studies with new terdentate ligands containing two 1,3,5-triazine moieties

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Publication details

The article was received on 09 Oct 2003, accepted on 18 Nov 2003 and first published on 05 Dec 2003


Article type: Paper
DOI: 10.1039/B312582C
Citation: Dalton Trans., 2004,0, 244-251
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    Solvent extraction and lanthanide complexation studies with new terdentate ligands containing two 1,3,5-triazine moieties

    M. G. B. Drew, C. Hill, M. J. Hudson, P. B. Iveson, C. Madic and T. G. A. Youngs, Dalton Trans., 2004, 0, 244
    DOI: 10.1039/B312582C

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