Variation of Thermodynamic Parameters in the Adduct Formation of β-Diketonato Chelates with 1, 10-Phenanthroline across the Lanthanoid Series
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The enthalpy change in the adduct formation of tris[1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato]lanthanoids (LnA<sub>3</sub>) with 1,10-phenanthroline (phen) as well as the formation constant of the adduct has been determined in chloroform across the lanthanoid series at 298 K by calorimetric titration and solvent-extraction techniques. The enthalpy change in the first adduct formation changes remarkably from light lanthanoids (endothermic) to heavy ones (exothermic), while the entropy change decreases largely from the middle to the heavy lanthanoids along with a small change from light to the middle of the series. Such a trend has been explained on the basis of the difference in the dehydration from lanthanoid(III) chelates and in the strength of the new bonding of chelates formed between tris(<i>β</i>-diketonato) lanthanoid(III) and phen across the lanthanoid series.
- Bulletin of the Chemical Society of Japan
Bulletin of the Chemical Society of Japan 71(12), 2825-2829, 1998-12-15
The Chemical Society of Japan