Electron structure of organometal complexes of f-elements.: 47.: On the elucidation of electron structure of η3-allyl compounds of lanthanides using the crystal field parameters of heteroallyl complexes

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 held (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 I-4(9/2), the experimentally determined temperature dependence of mu(eff)(2) could be reproduced. Compound 1 models the trigonal planar moiety of polymer pseudo trigonal-bipyramidal (eta(3)-C3H5)(3)Nd(mu-C4H8O2)(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.