Zur Elektronenstruktur metallorganischer Komplexe der f-Elemente XLVII. Gelingt die Aufklärung der Elektronenstrukturen von η3-Allylverbindungen der Lanthaniden anhand der Kristallfeld-Parameter von Heteroallylkomplexen?

Abstract

The absorption spectra of heteroallylic tris( N,N′-bis(trimethylsilyl)-4-methoxybenzamidinato)neodymium(III) ( 1) have been measured at room and low temperatures. From the spectra obtained, a truncated crystal field (CF) splitting pattern is derived, and simulated by fitting the free parameters of an empirical Hamiltonian. For 77 assignments an r.m.s. deviation of 33 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 calculated wavefunctions and the experimental CF energies of the ground manifold 4I 9/2, the experimentally determined temperature dependence of μ 2 eff could be reproduced. Compound 1 models the trigonal planar moiety of polymer pseudo trigonal-bipyramidal ( η 3-C 3H 5) 3Nd( μ-C 4H 8O 2) 2/2 ( 2) to a certain extent. On the basis of the optical analysis of 1, selected absorption transitions of 2 and model calculations in the framework of the angular overlap model, the CF parameters B 0 2 and B 0 4 of 2 are estimated.