Zur Elektronenstruktur metallorganischer Komplexe der f-Elemente XLVIII. Experimentelle Erfassung und parametrische Analyse der Elektronenstruktur von [Nd(#eta#~3-C_3H_5)_3 centre dot Dioxan_(2/2)] im f-Bereich

摘要

The absorption spectra of dimeric [{La(#eta#~3-C_3H_5)_3(C_4H_8O_2)}_2(#mu#-C_4H_8O_2)] (1) and polymeric [Nd(#eta#~3-C_3H_5)_3(C_4H_8O_2)_(22)] (2) have been measured at room and low temperatures. Comparing the spectra of both compounds, a truncated crystal field (CF) splitting pattern is derived for 2, and simulated by fitting the free parameters of an empirical Hamiltonian. For 40 assignments in the range below 17 250 cm~(-1) a reduced r.m.s. deviation of 33.5 cm~(-1) is achieved. The parameters derived allow the construction of experimentally-based non-relativistic and relativistic molecular orbital schemes in the f range. Making use of the wavefunctions of the fit the experimentally determined temperature dependence of #mu#_(eff)~2 could be reproduced. Presumably due to a stronger mixing of f and ligand orbitals the barycenters of higher multiplets in the vicinity of a charge transfer band are shifted strongly to lower energies.