Heteroleptic poly(pyrazolyl)borate derivatives of the lanthanides. Structural and electronic spectral studies of some salicylaldehyde complexes

The Dark Side of Hydrogen Bonds in the Design of Optical Materials: A Charge‐Density Perspective

“…The ρ ( r ) and ∇ 2 ρ ( r ) values in the BCPs of the hydrogen bonds are in the ranges of 0.09–0.21 e Å −3 and 1.6–2.8 e Å −5 , respectively, with a covalent contribution similar to that of the LnO bonds. Indeed, although interactions involving lanthanide ions are generally considered as fully ionic,29, 30 the negative electron energy densities, h e ( r ), for the LnO bonds provide evidence for their partially covalent character. The same follows from the luminescence data, namely from the experimental energy of the 5 D 0 level of the Eu 3+ ion (the nephelauxetic effect,31 E exp =17 100 cm −1 ).…”

Recent developments in the coordination chemistry of stable free radicals

“…The UV-visible spectra of these complexes featured a red-shifted absorption band (n-π*) that is also more intense and more structured relative to the uncoordinated radical 2. Excitation into the f-f absorption bands of europium(III) and terbium(III) complexes with nonradical ligands generally results in sharp luminescence [16]. However, emission from the europium(III) and terbium(III) tris(hfac) complexes with 2 following excitation into their f-f absorption bands was completely quenched as a result of overlap between the Ln(III) excited energy levels with the nitroxide-centered n-π* level.…”

Bis[3-(anthracen-9-yl)pentane-2,4-dionato-κ2 O,O′](N,N-dimethylformamide-κO)[tris(pyrazol-1-yl-κN 2)hydroborato]europium(III)

“…One of the compounds, FOLZUC, is discussed above and another, [tris(3-t-butyl-5-methylpyrazolyl)hydroborato](2,2,6,6-tetramethylheptane-3,5-dionato)ytterbium(II) (ESUJIL; Morissette et al, 2004) is a neutral molecule of Yb 2+ . Four entities are complexes with salicylaldehyde derivatives [JAJRAO (Onishi et al, 2004), QIDGAL, QIDGAL01 (Onishi et al, 1999), and ZUCCIJ (Lawrence et al, 1996)], which are also -diketonate anions, but, again, compounds with these anions contain eightcoordinate Ln 3+ ions.…”