Two series of lanthanide complexes have been chosen to analyze trends in the magnetic properties and crystal field parameters (CFPs) along the two series: The highly symmetric LnZn16(picHA)16 series (Ln=Tb, Dy, Ho, Er, Yb; picHA=picolinohydroxamic acid) and the [Ln(dpa)3](C3H5N2)3⋅3H2O series (Ln=Ce–Yb; dpa=2,6‐dipicolinic acid) with approximate three‐fold symmetry. The first series presents a compressed coordination sphere of eight oxygen atoms whereas in the second series, the coordination sphere consists of an elongated coordination sphere formed of six oxygen atoms. The CFPs have been deduced from ab initio calculations using two methods: The AILFT (ab initio ligand field theory) method, in which the parameters are determined at the orbital level, and the ITO (irreducible tensor operator) decomposition, in which the problems are treated at the many‐electron level. It has been found that the CFPs are transferable from one derivative to another, within a given series, as a first approximation. The sign of the second‐order parameter B02 differs in the two series, reflecting the different environments. It has been found that the use of the strength parameter S allows for an easy comparison between complexes. Furthermore, in both series, the parameters have been found to decrease in magnitude along the series, and this decrease is attributed to covalent effects.

with dipicolinic acid derivatives were synthesized and characterized by powder XRD, SQUID magnetometrya nd NMR spectroscopy.I na ddition, Np VI and Pu VI complexes were described by first principles CAS based and two-component spin-restricted DFT methods. The analysis of the 1 Hp aramagnetic NMR chemical shifts for all protons of the ligands according to the X-rays structures shows that the Fermi contact contribution is negligible in agreement with spin density determined by unrestrictedDFT.The magnetic susceptibility tensor is determined by combiningS QUID, pNMRs hifts and Evans' method. The SO-RASPT2 results fit well the ex-perimental magnetic susceptibility and pNMR chemical shifts.T he role of the counterions in the solid phaseisp ointed out;t heir presence impacts the magnetic properties of the Np VI complex.T he temperature dependence of the pNMR chemical shifts has as trong 1=T contribution, contrarily to Bleaney'st heory for lanthanide complexes. The fitting of the temperature dependence of the pNMR chemical shifts and SQUID magnetic susceptibility by at wo-Kramers-doublet model for the Np VI complex and an on-Kramers-doublet modelf or the Pu VI complex allows for the experimental evaluation of energy gaps and magnetic moments of the paramagnetic center.

The [An^IV(DPA)₃]²⁻ series with An = Th, U, Np, Pu has been synthesized and characterized using SC-XRD, vibrational spectroscopy, and first principles calculations.

The need for cost-efficient technologies for natural gas processing coupled with low environmental impact is becoming increasingly important due to the growing production of natural gas from subquality gas wells. The removal of nitrogen from such gas sources is especially challenging because of the similar properties of nitrogen and methane. This work studies the separation of an 85 mol% CH4 + 15 mol% N2 gas mixture by dual reflux pressure swing adsorption (DR PSA) using a N2-selective Engelhard titanosilicate type 4, ETS-4, as adsorbent via numerical simulations. Key DR PSA process parameters, such as the heavy product to feed flow ratio, the light reflux flow rate, and the feed step duration, were investigated to maximize the separation performance. In addition, productivity and energy requirements of the four DR PSA cycle configurations, namely PL-A, PH-A, PL-B and PH-B, were determined. The goal was to evaluate the capabilities of the nitrogen-selective ETS-4 in conjunction with the DR PSA process aiming to produce two useful product streams meeting pipeline specifications (> 93 mol% CH4) and environmental regulations (> 99 % N2). It was found that ETS-4 can easily upgrade the CH4 content of the gas mixture to pipeline specifications at high recovery but cannot meet the environmental regulations. The gas enriched in N2 needs to be further processed or can be used for electricity production via post-combustion.

With their high chemical and self-irradiation stability, crystalline monazites are among the most promising materials for the encapsulation of nuclear wastes. Yet, the local and magnetic structures of the matrices doped with low-content actinide cation, depicted as most resistant, are still unclear. This limits the development of theoretical approaches predicting their behavior under extreme conditionsself-irradiation and long-term leaching. Here, we characterize the model matrices La 1−x M x PO 4 (0 ≤ x ≤ 0.10)with M = Sm, 239 Pu, 241 Amby X-ray diffraction and solid-state 31 P NMR. As an example, we confirm that La 0.96 241 Am 0.04 PO 4 has higher self-irradiation resistance compared to 241 AmPO 4 . Further, computational analyses show that magnetic properties of the Pu complex are strongly affected by the J-mixing and the paramagnetic NMR shifts are dominated by the Fermi contact contribution, arising from delocalization of the spin density of the cation toward the phosphorus through the bonds.

two dipicolinic acid derivatives (DPA and Et-DPA) have been studied by 1 H and 13 C NMR spectroscopy and firstprinciples calculations. The Fermi contact and dipolar contributions to the Actinide Induced Shifts (AIS) are evaluated from a temperature dependence analysis, combined with ab initio results. It allows an experimental estimation of the axial anisotropy of the magnetic susceptibility Δ𝜒 𝑎𝑥 and of the hyperfine couplings constants of the NMR active nuclei. Due to the compactness of the coordination sphere, the magnetic anisotropy of the paramagnetic center is small, and this makes the contact contribution to be the dominant one, even on the remote atoms. The sign of the hyperfine coupling constants and related spin densities is alternating on the nuclei of the ligand cycle, denoting a preponderant spin polarization mechanism. This is well reproduced by unrestricted DFT calculations. Those values are furthermore slightly decreasing in the actinide series, which indicates a small decrease of the covalency from U IV to Pu IV .

We report on NMR spectroscopy, CAS-based method calculations, and X-ray diffraction of An V and An VI complexes with a neutral and slightly flexible TEDGA ligand. After checking that pNMR shifts mainly arise from pseudocontact interactions, we analyze pNMR shifts considering the axial and rhombic anisotropy of the actinyl magnetic susceptibilities. The results are compared to those of a previous study performed on [An VI O 2 ] 2+ complexes with dipicolinic acid. It is shown that 5f 2 cations (Pu VI and Np V ) make very good candidates for determining the structure of actinyl complexes in solution by 1 H NMR spectroscopy as shown by the invariance of the magnetic properties to the equatorial ligands, as opposed to the Np VI complexes with a 5f 1 configuration.

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