The hydration number and the stability of the adducts of tris[#beta#-diketonato] lanthanoids(III) with bidentate ligands in chloroform

摘要

The hydration number as well as the formation constants of the adducts of tris[pivaloyltrifluoroacetonato] lanthanoids(III) with 2,2'-bipyridyl(bpy) and l,l0-phenanthroline(phen) have been determined in chloroform across lanthanoid series using Karl-Fischer titration and solvent extraction techniques. The adducts of Ln(PTA)_3 with bpy and phen do not seem to have hydrated water molecules across lanthanoid series. The adduct formation constants increase with increasing the atomic number, but among the heavy lanthanoids, they do not change very much. Such a trend has been explained on the basis of the difference in the number of the dehydrated molecule and in the strength of the new bonding of adducts formed between Ln(PTA)_3 and bpy due to the difference of charge density across the lanthanoid series.