Electronic structures of organometallic complexes of f elements.: 60 [1] structural, single crystal optical and magnetooptical investigations on trialkylphosphate adducts of the tris(cyclopentadienyl)lanthanide(III) (Ln = La, Pr) moiety as well as results of comparing optical studies of [Pr(Ind)3(OP(OEt)3)] (Ind = indenyl)

[Ln(CP)(3)(OP(OR)(3))] (CP = eta(5)-cyclopentadienyl; Ln = La, R = Et (1); Ln = Pr, R Me (2); Ln = Pr, R - Et (3)) and [Pr(Ind)(3)(OP(OEt)(3))] (4) have been synthesized and spectroscopically as well as partly structurally (only compounds 1 and 2) characterized. On the basis of variable temperature measurements of a absorption spectra of an oriented single crystal, the magnetic circular dichroism spectra of dissolved, and the luminescence spectra of powdered material, a nearly complete crystal field (CF) splitting pattern could be derived for 3, and simulated by fitting the free parameters of a phenomenological Hamiltonian. The parameters used in the fit allowed the calculation of the global CF strength experienced by the Pr3+ central ion, the estimation of the nephelauxetic and relativistic nephelauxetic parameters, as well as the setup of experimentally based non-relativistic and relativistic molecular orbital schemes in the f range. The optical spectra of compound 4 suggest that two different species exist at low temperatures, thus preventing a successful CF analysis.