Zur Elektronenstruktur metallorganischer Komplexe der f-Elemente LII. Magnetochemische, optische und magnetooptische Charakterisierung von (η5-Cp)3Tm·THF

The absorption and magnetic circular dichroism spectra of the tetrahydrofuran adduct derived from tris(η5-cyclopentadienyl)thulium(III) (Cp3Tm·THF) were measured at low temperatures. The absorption spectra exhibit partly severe differences compared with the previously communicated band maxima and relative intensities of sublimed material. The observed more intense groups of signals comprise purely electronic f–f- as well as weaker vibronic transitions (where low frequency skeleton vibrations are coupling). Both types of bands could be separated by comparing these groups of signals with those of additional weaker vibronic transitions at higher frequencies (which have to be associated with the ν-CC vibration). In case of the multiplet 3F3 the resulting crystal field states are identified on an experimental as well as a calculated basis. Besides, the temperature dependence of μeff2 of the base adducts Cp3Tm·THF, Cp3Tm·MeTHF and Cp3Tm·CNC6H11 was determined and is compared with the result of a model calculation.