Ten substituted benzoate complexes of Pr³⁺ of the type [Pr(XC₆H₄COO)₃(H₂O)n(DMF)m]p·(DMF)q (X = OCH₃, NO₂, OH, F, Cl, NH₂) have been synthesized, and for eight of these crystallographic data are available. The electronic absorption and emission spectra of the complexes have been recorded and interpreted at temperatures down to 10 K for transitions involving the ³P₀ and ¹D₂ J-multiplet terms. Generally, the electron-withdrawing groups X in the benzoate moiety lead to higher ³P₀ energy than electron-donating groups. Empirical relations have been found between the energies of the ³P₀ and ¹D₂ (1) levels and the Hammett sigma constants for substituents and the unit cell volume per Pr³⁺ ion. The latter relationship is indicative of a correlation between the electronic state energy and the ligand dipole polarizability. This has been confirmed by reference to literature data for the LaX₃:Pr³⁺ systems, so that the ligand dipole polarizability is a key factor in determining the nephelauxetic shifts of 4fᴺ ions in crystals. Copyright © 2014 American Chemical Society.
|Journal||Journal of Physical Chemistry A|
|Early online date||Dec 2014|
|Publication status||Published - 2015|