Comprehensive Characterization of the Electronic Structure of U⁴⁺ in Uranium(IV) Phosphate Chloride

Abstract

Emerald-green single crystals of U(PO4)Cl were grown by chemical vapor transport in a temperature gradient (1000 → 900 °C). The crystal structure of U(PO4)Cl (Cmcm, Z = 4, a = 5.2289(7) Å, b = 11.709(2) Å, c = 6.9991(8) Å) consists of a three-dimensional network of [PO4] tetrahedra and bicapped octahedral [U(IV)O6Cl2] groups. Polarized absorption spectra measured for two perpendicular polarization directions show a large number of well-resolved electronic transitions. These transitions can be fully assigned on the basis of a detailed ligand-field treatment within the framework of the angular overlap model. The magnetic behavior predicted on the basis of the spectroscopic data is in agreement with an f (2) system and perfectly matched by the results of temperature-dependent susceptibility measurements.

Uranium(IV) Chloride Complexes: UCl62– and an Unprecedented U(H2O)4Cl4 Structural Unit

“…For 2 , the linear temperature dependence of the inverse magnetic susceptibility is typical for Curie–Weiss behavior and was fit to the Curie–Weiss equation 1/χ = C/( T – Θ CW ) in the temperature range of 300 K down to 100 K (Supporting Information, Figure S12). From the fit we obtain a Curie–Weiss temperature Θ CW = −384 K and an effective magnetic moment μ eff = 3.8 μ B , experimentally close to the expected value of 3.58 μ B calculated from Russell–Sanders coupling for a 3 H 4 ground state and in good agreement with previously reported investigations. − However, the ground state of 2 appears to be nonmagnetic, as seen in μ eff decreasing with decreasing temperature. This may be due to crystalline electric field (CEF) splitting as has been observed in Pr and U containing materials. , Unlike sample 2 , the magnetization of 1 behaves as a Pauli paramagnet with mostly temperature independent behavior.…”

A Theoretical Framework for Ratiometric Single Ion Luminescent Thermometers—Thermodynamic and Kinetic Guidelines for Optimized Performance

“…The preconstant C can be fixed by independent luminescence decay experiments at temperatures below T c . In the special case of trivalent lanthanides, both C and the emission branching ratios can alternatively be determined by Judd‐Ofelt theory with, e.g., the packages RELIC, [ 219 ] JOES, [ 220 ] LUMPAC [ 228,229 ] or, in principle also BonnMag [ 237–241 ] (see Equation 21). On the other hand, C can be independently obtained from the intercept of a Boltzmann plot in the validity regime of the Boltzmann equilibrium (see Figure 12), since …”

“…Usage of wavefunction-based post-Hartree-Fock approaches resulted in LUMPAC (Luminescence Package) [228,229] that employs semiempirical wavefunction methods and incorporates ORCA as a graphical user interface. [230,231] Recently, also ab initio multiconfigurational embedded cluster methods with a high level account of relativistic effects have been reported for Eu 3+ and Tb 3+ in cubic symmetries by Joos et al [232,233] Finally, the different approach by the angular overlap framework of ligand field theory [234][235][236] led to the development of the currently optimized program package BonnMag, [237][238][239][240][241] which allows for simultaneous ligand field and intensity calculations of lanthanide-based spectra even at lower symmetries than cubic ones. All those packages have the potential to perform computational studies on novel thermometers and give predictive tools at hand to facilitate experimental trial-and-error attempts and support the development of next-generation luminescence thermometers based on lanthanide dopants.…”

CONDON 3.0: An Updated Software Package for Magnetochemical Analysis‐All the Way to Polynuclear Actinide Complexes

“…Given the current and growing interest in homometallic and heterometallic coordination compounds of the nd –5 f and 5 f –5 f type, which display a wide range of interesting materials properties such as catalytic activity in small‐molecule activation and the hallmarks of a new generation of single‐molecule magnets (SMMs), the need for a highly efficient software package designed for the simulation and fitting of such actinide systems is evident. There are other software packages currently available that perform calculations involving isolated actinide centers, thus, not examining exchange interactions: for example, BonnMag, which utilizes the angular overlap model (AOM). Further software packages such as MOLCAS or ORCA are based on ab initio methods and do not allow for the treatment of exchange interactions in polynuclear complexes.…”