Electon-structured high-symmetry bonding of f-element. Part 33. First-time experimentalcrystal field analysis of a trigonal bipyramidal coordination lanthanide(III) system: Pr[N(SiMe3)2]3(CNR)2 (R = tBu, C6H11)

Article abstract of DOI:10.1016/S1386-1425(01)00547-9

The absorption und magnetic circular dichroism spectra of the dissolved trigonal-bipyramidal complex Pr[N(SiMe₃)₂]₃(CN^tBu) ₂ (1) as well as the luminescence and absorption spectra of both solid 1 and solid Pr[N(SiMe₃)₂]₃(CNC₆ H₁₁)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 compunds a reliable crystal field (CF) splitting pattern for the ground manifold ³H₄, but only a plausible for the f² configuration could be derived on the basis of these measurements. The latter could be simulated with a reduced r.m.s. deviation of 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 temperature dependence of μ_eff² for compund 1. The CF parameters of this fit are considered as a master set of CF parameters for future CF analyses of the electronic structures of trigonal bipyramidally coordinated lanthanide(III) systems.