Electronic structures of highly symmetrical compounds of f elements. 36 - Parametric analysis of the optical spectra of an oriented tris(hydrotris(1-pyrazolyl)borato)praseodymium(III) single crystal

The absorption and luminescence spectra of polycrystalline tris(hydrotris(I-pyrazolyl)borato)-praseodymium(III) (PrTP3) were measured at room temperature as well as at low temperatures. At room temperature the "polarized" luminescence spectra of a small oriented PrTP3 single crystal could also be recorded. On the basis of these spectroscopic findings the underlying crystal field splitting pattern could be derived, and simulated by fitting the free parameters of a phenomenological Hamiltonian, achieving a reduced r.m.s. deviation of 17.3 cm(-1) for 37 assignments. On the basis of the parameters used, the global ligand field strength experienced by the Pr3+ central ion as well as the individual ligand field strength associated with one Tp ligand are determined, nephelauxetic and relativistic nephelauxetic effects are estimated, and the experimentally orientiented nonrelativistic and relativistic molecular orbital schemes in the f range are set up.