Optical absorption spectra, crystal-field analysis, and electric dipole intensity parameters for europium in Na3[En(ODA)3]-2NaClO4·6H2O

Ab Initio Investigation of the Na3[Ln(ODA)3]·2NaClO4·6H2O (Ln = Ce-Yb; ODA = Oxydiacetate) Series

In this work, the Na₃[Ln(ODA)₃]·2NaClO₄·6H₂O (Ln = Ce-Yb; ODA = oxydiacetate) series was analyzed with the ab initio ligand field theory (AILFT) module of the ORCA computational suite. The results were discussed within the framework of the angular overlap model (AOM) and compared to literature data. We find that the structural changes observed across the series exemplifies the effects of the lanthanide contraction also manifesting in the value of the AOM parameters. It is also shown that the complete active space self-consistent field (CASSCF) methodology is sufficient to describe the ligand field interactions in mononuclear lanthanide complexes, and the effects of dynamic correlation, through n-electron valence state perturbation theory (NEVPT2), are discussed. The calculated ligand field parameters of the present work are compared to the experimentally derived values from the literature.

What factors affect the 5D0 energy of Eu3+? An investigation of nephelauxetic effects

Relationships involving the interelectronic repulsion parameters, F(k) (k = 2, 4, 6), the spin-orbit coupling constant, ζf, and J-mixing, with the (5)D0-(7)F0 energy, E, have been investigated for Eu(3+) using various approaches. First, the linear relationship between E and the (7)F1 splitting (or the second rank crystal field parameter) is shown to be applicable not only to glasses but also to solid-state crystalline systems with Eu(3+) site symmetry of C2, C2v, or lower. In these cases, the change in (5)D0-(7)F0 energy is mainly due to the J-mixing effect of (7)F(J) (J = 2, 4, 6: most notably J = 2) which depresses (7)F0, whereas the (5)D0 energy is relatively constant. The (5)D0-(7)F0 energy also depends upon certain energy parameters in the Hamiltonian, in particular, F(k) and ζf. Model calculations show that increase in F(4) or F(6) produces an increase in E, whereas increase in F(2) produces a decrease in E. An increase in ζf produces a decrease in E. These findings are rationalized. Most previous 4f(6) crystal field calculations have only considered the F and D terms of Eu(3+) so that the Slater parameters are not well-determined. More reliable energy level data sets and crystal field calculations for Eu(3+) with fluoride, oxide, or chloride ligands have been selected, and certain of these have been repeated since most previous calculations have errors in matrix elements. The fitted Slater parameters have been corrected for the effects of three-body Coulomb interactions. Some systems do not follow the ligand trend F ~ O > Cl for Slater and spin-orbit parameters. From the limited data available, the average values of the corrected Slater parameters are greater for fluoride compared with chloride ligands, but the differences are comparable with the standard deviations of the parameters. There is no clear nephelauxetic series for these three types of ligands, with respect to spin-orbit coupling. Previous correlations of E with various parameters are of limited value because the (5)D0-(7)F0 energy difference not only depends upon the F(k) and ζf parameters but in addition is sensitive to the importance of J-mixing for low symmetry systems.

Electronic State Structure and Optical Properties of Tb(oda)(3)(3)(-) Complexes in Trigonal Na(3)[Tb(oda)(3)].2NaClO(4).6H(2)O Crystals

Polarized optical absorption and emission measurements are used to locate and assign 95 crystal-field energy levels split out of the 4f( )(8) electronic configuration of Tb(3+) in single crystals of Na(3)[Tb(oda)(3)].2NaClO(4).6H(2)O (where oda denotes an oxydiacetate ligand). The absorption measurements span the 235-490 nm wavelength range, and the emission measurements span the 485-685 nm wavelength range. The combined absorption and emission spectra measurements provide access to the energy-level structures of 46 different 4f( )(8)[SL]J multiplet manifolds of Tb(3+) (all multiplet manifolds with baricenter energies <42 400 cm(-)(1) above ground). The site symmetry of the Tb(3+) ions in Na(3)[Tb(oda)(3)].2NaClO(4).6H(2)O is D(3), and the point-group symmetry of the tris-terdentate Tb(oda)(3)(3)(-) coordination complexes is also D(3). The Tb(oda)(3)(3)(-) complexes are chiral, and they exist in just one, fully resolved enantiomeric form in single crystals of Na(3)[Tb(oda)(3)].2NaClO(4).6H(2)O. The crystals exhibit strong chiroptical activity in their absorption and emission spectra, and results obtained from both circularly polarized and linearly polarized optical spectra measurements are used in making transition line assignments. The energy-level data acquired from the spectroscopic measurements are analyzed in terms of a model Hamiltonian that includes consideration of both isotropic and nonisotropic 4f electron/crystal-field interactions, and the interaction parameters derived from this analysis are discussed and then compared with those obtained for other Na(3)[Ln(oda)(3)].2NaClO(4).6H(2)O systems and for Tb(3+) in other crystalline hosts.