Zur Elektronenstruktur metallorganischer Komplexe der f‐Elemente. 67 Erstmalige parametrische Analyse des Absorptionsspektrums einer Molekülverbindung des CeIIIμ: Tris(η5‐tetramethylcyclopentadienyl)cer

Abstract

AbstractElectronic Structures of Organometallic Complexes of f Elements. 67 First Parametric Analysis of the Absorption Spectrum of a Molecular Compound of CeIIIμ: Tris(η5‐tetramethylcyclopentadienyl)cerium(III)The absorption spectra (in the IR/NIR/Vis/UV range) of Ce(C5Me4H)3 (1) and La(C5Me4H)3 (2) were recorded at room and low temperatures. From the spectra obtained, two alternative closely related crystal field (CF) splitting patterns of 1 could be derived, and simulated by fitting the free parameters of a phenomenological Hamiltonian. The fact that the difference of the experimental energies of the barycenters of CF levels of the multiplets 2F7/2 and 2F5/2 is larger than in the gaseous free Ce3+ ion (“anti”‐relativistic nephelauxetic effect) could be explained by coupling effects of these multiplets via the CF, resulting in lower spin‐orbit coupling parameters than in the case of the gaseous free Ce3+ ion. The experimentally derived CF splitting pattern of 1 is compared with the predictions of previous non‐relativistic SW‐Xα and relativistic DV‐Xα calculations.