Temperature Dependence of 1H Paramagnetic Chemical Shifts in Actinide Complexes, Beyond Bleaney's Theory: The AnVIO22+–Dipicolinic Acid Complexes (An=Np, Pu) as an Example

Autillo, Matthieu; Islam, Md Ashraful; Héron, Julie; Guérin, Laetitia; Acher, Eléonor; Tamain, Christelle; Illy, Marie-Claire; Moisy, Philippe; Colineau, E.; Griveau, Jean‐Christophe; Berthon, Christophe; Bolvin, Hélène

doi:10.1002/chem.202005147

Cited by 12 publications

(37 citation statements)

References 85 publications

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“…The δ FCS contribution, as expressed in eqs S2–S5 and refs and , depends on the spin contribution to the magnetic susceptibility χ S from the paramagnetic center and, on the spin density at the NMR active nucleus K ρ S ( r K ). A full theoretical determination of δ FCS was, unfortunately, not possible due to the difficulty in computing the term K ρ S ( r K ).…”

Section: Resultsmentioning

confidence: 99%

Local Structure and Magnetism of La_1–xM_xPO₄ (M = Sm, ²³⁹Pu, ²⁴¹Am) Explained by Experimental and Computational Analyses

et al. 2021

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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.

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Section: Resultsmentioning

confidence: 99%

Local Structure and Magnetism of La_1–xM_xPO₄ (M = Sm, ²³⁹Pu, ²⁴¹Am) Explained by Experimental and Computational Analyses

et al. 2021

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“…The computational approach focuses then on the ab initio evaluation of the anisotropy of the χ tensor. This allows the full description of the paramagnetic center with all excited states, either partially populated or not, and strongly magnetically coupled . We will follow this approach in this work.…”

Section: Introductionmentioning

confidence: 97%

“…21 It has early been shown that a T −3 correction term can be necessary 22 and this was recently successfully applied in the [Ln III (DPA)3] 3-, [An III (DPA)3] 3and [An VI O2(DPA)2] 2-. 11,23 The computation from first principles of pNMR shifts requires a balanced description of the multiconfigurational electronic structure of the paramagnetic center in order to describe its magnetic susceptibility, and, of the metal-ligand spin delocalization and polarization for the contact contribution. Many computational approaches to calculate pNMR shieldings are based on Kurland-McGarvey theory.…”

Section: Introductionmentioning

confidence: 99%

“…This allows the full description of the paramagnetic center with all excited states, either partially populated or not, and strongly magnetically coupled. 23 We will follow this approach in this work. The Fermi contact term is better described using DFT in an unrestricted scheme.…”

Section: Introductionmentioning

confidence: 99%

“…Alternative methods to separate the two contributions are based on the respective T –1 and T –2 temperature dependences of the Fermi contact and pseudocontact contributions. , Limiting the thermal expansion to those two terms has been criticized . It has earlier been shown that a T –3 correction term can be necessary, and this was recently successfully applied in [Ln III (DPA) 3 ] 3– , [An III (DPA) 3 ] 3– , and [An VI O 2 (DPA) 2 ] 2– . , …”

Section: Introductionmentioning

confidence: 99%

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Dipolar and Contact Paramagnetic NMR Chemical Shifts in An^IVComplexes with Dipicolinic Acid Derivatives

et al. 2022

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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 .

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Analysis of the Magnetic Coupling in a Mn(II)‐U(V)‐Mn(II) Single Molecule Magnet

Dey

Rajaraman

Bolvin

2022

Chemistry A European J

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{Mn(TPA)I}{UO2(Mesaldien)}{Mn(TPA)I}]I formula (here TPA = tris(2-pyridylmethyl)amine and Mesaldien = N,N'-(2-aminomethyl)diethylenebis(salicylidene imine)) reported by Mazzanti and coworkers (Chatelain et al. Angew. Chem. Int. Ed. 2014, 53, 13434) is so far the best Single Molecule Magnet (SMM) in the {3d-5f} class of molecules exhibiting barrier height of magnetization reversal as high as 81.0 K. In this work, we have employed a combination of ab initio CAS and DFT methods to fully characterize this compound and to extract the relevant spin Hamiltonian parameters. We show that the signs of the magnetic coupling and of the g-factors of the monomers are interconnected. The central magnetic unit [U V O2] + is described by a Kramers Doublet (KD) with negative g-factors, due to a large orbital contribution. The magnetic coupling for the {Mn(II)-U(V)} pair is modeled by an anisotropic exchange Hamiltonian: all components are ferromagnetic in terms of spin moments, the parallel component JZ twice larger as the perpendicular one J ⊥ . The spin density distribution suggests that spin polarization on the U(V) center favors the ferromagnetic coupling. Further, the JZ /J ⊥ ratio, which is related to the barrier height, was found to correlate to the corresponding spin contribution of the g-factors of the U(V) center. This correlation established for the first time offers a direct way to estimate this important ratio from the corresponding g S -values, which can be obtained using traditional ab initio packages and hence has a wider application to other {3d-5f} magnets. It is finally shown that the magnetization barrier height is tuned by the splitting of the [U V O2] + 5f orbitals.

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Temperature Dependence of ¹H Paramagnetic Chemical Shifts in Actinide Complexes, Beyond Bleaney's Theory: The An^VIO₂²⁺–Dipicolinic Acid Complexes (An=Np, Pu) as an Example

Cited by 12 publications

References 85 publications

Local Structure and Magnetism of La_1–xM_xPO₄ (M = Sm, ²³⁹Pu, ²⁴¹Am) Explained by Experimental and Computational Analyses

Local Structure and Magnetism of La_1–xM_xPO₄ (M = Sm, ²³⁹Pu, ²⁴¹Am) Explained by Experimental and Computational Analyses

Dipolar and Contact Paramagnetic NMR Chemical Shifts in An^IVComplexes with Dipicolinic Acid Derivatives

Analysis of the Magnetic Coupling in a Mn(II)‐U(V)‐Mn(II) Single Molecule Magnet

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Temperature Dependence of 1H Paramagnetic Chemical Shifts in Actinide Complexes, Beyond Bleaney's Theory: The AnVIO22+–Dipicolinic Acid Complexes (An=Np, Pu) as an Example

Cited by 12 publications

References 85 publications

Local Structure and Magnetism of La1–xMxPO4 (M = Sm, 239Pu, 241Am) Explained by Experimental and Computational Analyses

Local Structure and Magnetism of La1–xMxPO4 (M = Sm, 239Pu, 241Am) Explained by Experimental and Computational Analyses

Dipolar and Contact Paramagnetic NMR Chemical Shifts in AnIVComplexes with Dipicolinic Acid Derivatives

Analysis of the Magnetic Coupling in a Mn(II)‐U(V)‐Mn(II) Single Molecule Magnet

Contact Info

Product

Resources

About

Temperature Dependence of ¹H Paramagnetic Chemical Shifts in Actinide Complexes, Beyond Bleaney's Theory: The An^VIO₂²⁺–Dipicolinic Acid Complexes (An=Np, Pu) as an Example

Local Structure and Magnetism of La_1–xM_xPO₄ (M = Sm, ²³⁹Pu, ²⁴¹Am) Explained by Experimental and Computational Analyses

Local Structure and Magnetism of La_1–xM_xPO₄ (M = Sm, ²³⁹Pu, ²⁴¹Am) Explained by Experimental and Computational Analyses

Dipolar and Contact Paramagnetic NMR Chemical Shifts in An^IVComplexes with Dipicolinic Acid Derivatives