Zur Elektronenstruktur hochsymmetrischer Verbindungen der f‐Elemente. 40. Parametrische Analyse des Kristallfeld‐Aufspaltungsmusters von Tris(hydrotris(1‐pyrazolyl)borato)neodym(III)

Abstract

Electronic Structures of Highly Symmetrical Compounds of f Elements. 40. Parametric Analysis of the Crystal Field Splitting Pattern of Tris(hydrotris(1‐pyrazolyl)borato)neodymium(III) The absorption spectrum of tris(hydrotris(1‐pyrazolyl)borato)neodymium(III) (NdTp3) was run at room and low temperatures. From the spectra obtained, a truncated crystal field (CF) splitting pattern could be derived, and simulated by fitting the free parameters of a phenomenological Hamiltonian achieving an r.m.s. deviation of 11.0 cm−1 for 48 assignments. The parameters used allow the estimation of the ligand field strength experienced by the Nd3+ central ion, the insertion of the Tp ligand into empirical nephelauxetic and relativistic nephelauxetic series, and the set‐up of experimentally based nonrelativistic molecular orbital schemes in the f range.

Properties of uranium- and lanthanide-based single-ion magnets modelled by the complete and restricted Hamiltonian approach

“…Hence, the CFPs that would yield the same energies by diagonalization of H CF (J) in the Stevens formalism using the LS-coupling within the ground J multiplet may differ markedly from those obtained from analysis of the experimental optical spectra using the complete approach, since in the former case they are scaled to compensate poorly determined RMEs values [11][12][13][14][15][16]. For quantitative comparison of the quality of the modelling obtained using the two approaches, one may consider the CFPs for Nd(III) ions in NdTp 3 determined by Reddmann et al [22] and independently by us from absorption spectra as: B 20 = -512, B 40 = -969, B 60 = 153, and B 66 = 828 (in cm -1 ). The CFP values obtained in the restricted approach were reported therein [20], which after conversion to the Wybourne notation yield: B 20 = -80, B 40 = -884, B 60 = 110, B 66 = 695 (in cm -1 ).…”

“…The experimental energy levels data obtained by optical spectroscopy for both UTp 3 [23] and NdTp 3 [22] have been utilized by us for fine-tuning of the CFPs B kq and subsequently for determination of the energies (sets denoted (OS) in Table 1) as well as the wave functions using the complete approach [11][12][13][14][15][16]. The differences between the energies obtained in the two approaches reflect quantitatively the fact that using the restricted approach for analysis of data derived from magnetic measurements the so-obtained CFPs, k q k r A , are optimized with respect to the lowest energy components of the ground multiplet only.…”

“…These sets, denoted in Table 1 as 'Complete(OS)', were determined by independent fittings of the energy levels obtained from optical absorption spectra by Reddmann et al [22] for NdTp 3 and Apostolidis et al [23] for UTp 3 . These fine-tuned CFPs B kq , which turned out to be the same as those listed therein [22,23] (apart from the rounding errors), were used in the complete approach. Table 1 The energies of the ground multiplet components calculated for Dy(III) ion in Dy(H 2 BPz Me2 2 ) 3 , Nd(III) ion in NdTp 3 and U(III) in U(H 2 BPz 2 ) 3 and U(Ph 2 BPz 2 ) 3 using the restricted or complete approach; for explanations, see text.…”

“…The CFP values obtained in the restricted approach were reported therein [20], which after conversion to the Wybourne notation yield: B 20 = -80, B 40 = -884, B 60 = 110, B 66 = 695 (in cm -1 ). Additionally, we note that the CFP B 20 was determined [22] from spectroscopic data also for PrTp 3 In the case of UTp 3 complex our independent CF analysis, carried out in the complete approach and based on the absorption spectra [23], yielded the CFPs in the Wybourne notation (in cm -1 ): B 20 = -1124, B 40 = -2457, B 60 = 440, and B 66 = 2529, which are very close to those reported therein [23]. These CFP values differ significantly from those determined in the restricted approach reported in Table S3 , some authors [17,18,19,20] have attempted to predict the magnetic anisotropy properties of SIMs.…”

“…The merit and applicability of the PCE model for the rationalization of the magnetic properties of f-element ions remains an open question. Due to availability of the experimental optical spectroscopy data [22,23] for both UTp 3 and NdTp 3 , comparison of the respective modelling predictions obtained using the PCE model [17,20] with the experimental data is also feasible. To the best of our knowledge, this study is the first of this kind and has important implications for understanding applicability of the models used for description of electronic structure of SIMs as well as SMMs.…”