Electron structure of organometal complexes of f-elements. 56. Parametric analysis of crystal field splitting patterns of pseudo-trigonal-bipyramidal coordinated O-donor and P-donor functionalized ethylcylopentadienyl complexes of neodymium(III)

The absorption spectra of pseudo trigonal bipyramidally coordinated Nd(eta(5)-C5H4CH2CH2OMe)(3) (1) and Nd(eta(5)-C5H4CH2CH2PMe2)(3) (2) have been measured at room and low temperatures. From the spectra obtained, truncated crystal field (CF) splitting patterns of these compounds are derived, and simulated by fitting the parameters of a phenomenological Hamiltonian. For 55 and 53 assignments, respectively, reduced r.m.s. deviations of 31 and 23 cm(-1) are achieved for complexes 1 and 2. The parameters derived allow the estimation of the crystal field strength experienced by the Nd 31 central ions of compounds 1 and 2, the insertion of these complexes into truncated empirical nephelauxetic and relativistic nephelauxetic series, and the setup of their experimentally-based non-relativistic and relativistic molecular orbital schemes in the f range. (C) 2003 Published by Elsevier Science B.V.