Electronic Structure of Organometallic Complexes of f Elements. Are Molecular Orbital Calculations a Useful Tool for Spectroscopists?

Abstract

The crystal field parameters of base-free (Me 3 SiC5 H4 )3 Pr, (C5 H 5 )3 Pr.ΝCCH 3 , (C5 H5 ) 3 La(ΝCCH3 ) 2 :Pr, [Ρr(C8 H8 )]+ and Νd[Ν(SiMe3 ) 2 ]3 as model compound for Νd[CH(SiMe 3 ) 2 ]3 were inserted into the corresponding energy matrices of a model spin-free f1 system. Diagonalizing these matrices the crystal field splitting patterns of the f orbitals were calculated. These experimentally based molecular orbital schemes are compared with the results of previous model calculations.

Crystal Field Strengths, Nephelauxetic Effects, and Experimentally Based Molecular Orbital Schemes (in the f Range) of Selected Cyclopentadienyl Complexes of Samarium(III)

“…[45] Inserting the CF parameters of compounds 1؊5 into the relation below [2] were found, [7,48] (Table 3) which is mainly due to the decreasing absolute value of B 0 2 within this series. The results [49] of basic model calculations in the framework of the angular overlap model [50Ϫ52] are consistent with the found trend for the above mentioned compounds ( Table 3 . [53] Applying method A on compound 1 and method B on complex 2, C 5 H 4 tBu Ϫ and unsubstituted Cp produce CF strengths of 583 and 522 cm Ϫ1 , respectively.…”

“…[49] as the experimentally based non-relativistic MO scheme of this compound in the f range. Likewise, the eigenvalues of an energy matrix of the real f 1 system, into which the spin-orbit coupling as well as the CF parameters had been inserted, were defined as the experimentally based relativistic MO scheme of this compound in the f range.…”

“…Going from the fictive base-free trigonal planar [Ln(Cp) 3 ] complex via a trigonal pyramidal mono to a trigonal bipyramidal bis base adduct, the axially f z 3 orbital should be increasingly energetically destabilized adopting the approximation of the angular overlap model. [49] (Figure 7). …”

Electronic structures of organometallic complexes of f elements LXXIII: Parametric analysis of the crystal field splitting pattern of tris(η5-pentamethylcyclopentadienyl)cerium(III)

“…If sufficient CF levels are detected, the free parameters of a phenomenological Hamiltonian can be fitted to the experimentally derived CF splitting pattern. The parameters obtained allow the insertion of CeCp* 3 into empirical spectrochemical and relativistic nephelauxetic series [14] and the set-up of the experimentally oriented non-relativistic molecular orbital (MO) scheme of 1 (in the f range [15]), which can be compared with the results of a previous non-relativistic SW-Xa calculation on the w trigonal planar model complex Ce(g 5 -C 5 H 5 ) 3 [16]. Likewise, the predicted CF splitting pattern of Ce(g 5 -C 5 H 5 ) 3 [17] (relativistic DV-Xa approximation) as well as the predictions of the energies of f ?…”

Electronic structures of organometallic complexes of f elements LXVI

“…From the parameters found, the [C 5 Me 4 H] À ligand can be inserted into empiric spectrochemical, nephelauxetic and relativistic nephelauxetic series of Sm III compounds. Also, the experimentally-based non-relativistic molecular orbital (MO) scheme (in the f range) [11] of 1 can be set up, and will be compared with the results of a previous Xa-SW calculation on the w trigonal planar model complex Sm(g 5 -C 5 H 5 ) 3 [12].…”