Electron structure of highly symmetric compounds of f-elements.: Part 33:: First experimental derivation of crystal field parameters of a trigonal-bipyramidal lanthanide(III) complex:: Pr[N(SiMe3)2]3(CNR)2 (R = tBu, C6H11)

The absorption und magnetic circular dichroism spectra of the dissolved trigonal-bipyramidal complex Pr[N(SiMe3)(2)](3)((CNBu)-Bu-t)(2) (1) as well as the luminescence and absorption spectra of both solid 1 and solid Pr[N(SiMe3)(2)](3)(CNC6H11)(2) (2) (pellets, unoriented single crystals) were measured at ambient and low temperatures. Because of the violation of the selection rules for D-3h symmetry by both Compounds a reliable crystal field(CF) splitting pattern for the ground manifold H-3(4), but only a plausible for the f(2) configuration could be derived on the basis of these measurements. The latter could be simulated with a reduced r.m.s. deviation or 32.6 cm(-1) for 29 assignments by fitting the free parameters of a phenomenological Hamiltonian. The adequacy of the calculated wavefunctions of this fit in the low energy range is proved by the excellent agreement of calculated and experimental, eff temperature dependence of mu (2)(cff) for compound 1. The CF parameters of this fit are considered as a "master set" of CIF parameters for future CF analyses of the electronic structures of trigonal bipyramidally coordinated lanthanide(III) systems. (C) 2002 Elsevier Science B.V. All rights reserved.