Formation constants of trivalent lanthanide metal ions and hydrazone β-diketones in 75% dioxane – water solvent

Abstract

A new series of hydrazone P-diketone organic ligands were prepared: 3-(2-acetylpheny1hydrazone)pentane-2,4-dione (2-APHA), 2-(2-acetylpheny1hydrazone)-1-phenyl-1,3-butane dione (2-APHB), 2-(2-acetylpheny1hydrazone)-1,3-diphenyl-1,3-propane dione (2-APHDB), 3-(2-acetylphenylhydrazone) 1,1,1-trifluoropentane-2,4-dione (2-APHTA) and 2-(2-acetylpheny1hydrazone)-5,5-dimethyl-1,3-cyclohexane dione (2-APHDm). The step formation constants of their 1:l and 1:2 rare-earth complexes were determined at 30°C by pH titration in 75% (v/v) dioxane-water solvent. The ionization constant of ligands were also measured. A curious odd-even stability differential was apparent in the (2-APHDm) ligand with the heavier rare earths Gd-Lu. The differential was apparent in both log K , and log P values and may be sufficient to cause reversal of the usual ion-exchange elution sequence. On a prCparC une nouvelle skrie de ligands organiques dCrivts d'hydrazones de P-dicttones : (acCtyl-2 phCny1hydrazone)-3 pentanedione-2,4 (2-APHA), (acCtyl-2 phCny1hydrazone)-2 phtnyl-1 butanedione-1,3 (2-APHB), (acttyl-2 phCny1hydrazone)-2 diphCnyl-1,3 propanedione-1,3 (2-APHDB), (acCtyl-2 phtny1hydrazone)-3 trifluoro-1 , 1 , 1 pentanedione-2,4 (2-APHTA) et (acCtyl-2 phCny1hydrazone)-2 dimkthyl-5,5 cyclohexanedione-1,3 (2-APHDm). Operant a 30°C, dans un mClange dioxanneleau i 75% (v/v), on a dCterminC les constantes de formation par ttape de leurs complexes I: 1 et 1:2 avec des terres rares. On a aussi mesurC la constante d'ionisation des ligands. On a determink qu'il existe une curieuse de stabilitt diffkrentielle dans les complexes pair et impair du ligand 2-APHDm avec les terres rares plus lourdes de la strie Gd a Lu. On peut remarquer les differences tant dans les valeurs du log K , que du log P et ces differences sont telles qu'elles peuvent &tre suffisantes pour renverser la stquence habituelle d'Clution lors de l'tchange d'ions.[Traduit par la revue] P-Diketones are well-known chelating agents, capable of forming stable complexes with metal ions. Lanthanide Pdiketones have also been found to have wide application (2), including chromatographic separation of the lanthanide series (3). Azo compounds are also used as complexing agents (4), and the combination of azo compounds and P-diketones are good ligands (5). The chelation between similar ligands and lanthanide metal has been studied (6, 7).The coupling product of the diazonium salt of 2-aminoacetophenone with-different P-diketones such as acetylacetone, benzoylacetone, dibenzoyl methane, trifluoroacetylacetone, and 5,5-dimethylcyclohexane-1,3-dione (dimedone) produces a series of 3-(2-acetylphenylhydrazone)diketone ligands. T h e present study determined the acid dissociation constants of these ligands and the formation constants of their trivalent lanthanide complexes. The structure and basicity effects of the ligands on the stability of the formed complexes are discussed and some correlations attempted. These complexing agents may be useful in the separation of the lanthanides. Experimental (i) Ma...

Lanthanide complexes of D-penicillamine: formation constants, spectral and thermal properties

“…This deviation from linearity beyond Gd has been attributed to change in hydration along the series [35]. This kind of behavior has been observed for a variety of lanthanide complexes [48,49]. Different magnitudes of the formation constants of the complexes are manifested in different concentrations of the complex species.…”

Fluorine-Containing 2-Functionalized 1,3-Dicarbonyl Compounds for Heterocyclic Synthesis

“…Polyfluoroalkyl-containing 1,3-diketones (2) are coupled with aryl-and (antipyrin-4-yl)diazonium chlorides in the presence of sodium acetate to afford 2-arylhydrazones of 1,2,3-triketones (6) (Scheme 3). [11][12][13][14][15][16][17][18] The IR and NMR spectra of compounds (5,6) indicate their presence in the CHCl 3 solution and in the crystals as a hydrazono-diketo tautomer, although both keto-enol and azo-hydrazone tautomerisms are possible for these compounds. 11,12,18 Polyfluoroalkyl-containing 1,2,3-triketones 2-hetarylhydrazones (A) were not isolated from the reactions of 1,3-diketones (2) with hetarylamine that has NH-group at the α-position of heterocycle as the diazonium component (4-ethoxycarbonylpyrazol-3-yl-and 1,2,4-triazol-3-yl diazonium chlorides).…”

Azo Complexes of Cu(II), Co(II), Ni(II), Cd(II), Th(IV), and UO2(VI) Ions. Mixed‐Ligand Complexes, Pyrolysis Products and Biological Activity

“…These solvents were reagent grade. The organic ligand (H 2 L) was prepared by literature methods [11,12] through coupling the diazonium salt 2-aminobenzoic acid with 5,5-dimethyl-1,3-cyclohexanedione. The coupling occurs in sodium acetate medium.…”