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A uranium-based UO2(+)-Mn2+ single-chain magnet assembled trough cation-cation interactions.

Mougel V, Chatelain L, Hermle J, Caciuffo R, Colineau E, Tuna F, Magnani N, de Geyer A, Pécaut J, Mazzanti M - Angew. Chem. Int. Ed. Engl. (2013)

Bottom Line: The 5f-3d heterometallic 1D chains [{[UO2(salen)(py)][M(py)4](NO3)}]n, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO2(salen)py][Cp*2Co] (Cp*=pentamethylcyclopentadienyl) with Cd(NO3)2 or Mn(NO3)2 in pyridine.The infinite UMn chain displays a high relaxation barrier of 134±0.8 K (93±0.5 cm(-1)), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group.It also exhibits an open magnetic hysteresis loop at T<6 K, with an impressive coercive field of 3.4 T at 2 K.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Reconnaissance Ionique et Chimie de Coordination SCIB, UMR-E3 CEA-UJF, INAC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 09 (France) http://inac.cea.fr/Pisp/51/marinella.mazzanti.html.

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Plots of a) χT vs. T and b) ln (χT) vs. 1/T for a polycrystalline sample of 2 measured at 0.05 T applied field.
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fig02: Plots of a) χT vs. T and b) ln (χT) vs. 1/T for a polycrystalline sample of 2 measured at 0.05 T applied field.

Mentions: Variable-temperature (2–300 K) magnetic susceptibility measurements were performed on polycrystalline samples of 1 and 2 in static magnetic fields ranging from 0.01 to 5 T (Figure 2 and the supplementary information). The measured χT value for 2 at room temperature is approximately 4.3 cm3 K mol−1; considering that the susceptibility curves for the Cd-based analogue 1 (see the Supporting Information) point towards a much smaller χT value (below 0.3 cm3 K mol−1) we can conclude that this value is in line with what is expected for one spin-only divalent manganese (with S=5/2 and g close to 2) and one pentavalent uranium ion, whose magnetic moment is significantly reduced with respect to the free-ion value by the combined effect of ligand field and covalent bonding.19 The χT product decreases with decreasing temperature to 4.1–4.2 cm3 K mol−1 at 150 K; the fact that the same quantitative behavior is observed for 1 and that the decrease is similar in absolute value for the two compounds, allows the attribution of this effect to the ligand-field state depopulation for the anisotropic uranium centers, whereas the contribution of the more isotropic manganese ions can be approximately regarded as constant within this temperature range. Below 150 K, the susceptibility of 2 increases to reach a field-dependent maximum, with values of 56.8 cm3 K mol−1 at 0.01 T (Figure S9) and 52.7 cm3 K mol−1 at 0.05 T (Figure 2), before dropping rapidly at very low temperatures owing to saturation effects, magnetic anisotropy, and possibly inter-chain antiferromagnetic interactions. The increase of χT below 150 K, as well as the strong deviation from the Curie–Weiss behavior of χ−1 vs. T (see the Supporting Information), suggests dominant ferromagnetic interactions leading to an aligned-spin ground state. None of this is observed for the Cd-based analogue 1, where only an abrupt decrease of the χT product below 25 K is observed, which is most likely due to single-ion crystal field effects associated with UV,8a quenching of the orbital angular momentum, and possibly weak next-nearest-neighbor antiferromagnetic exchange between uranium centers.


A uranium-based UO2(+)-Mn2+ single-chain magnet assembled trough cation-cation interactions.

Mougel V, Chatelain L, Hermle J, Caciuffo R, Colineau E, Tuna F, Magnani N, de Geyer A, Pécaut J, Mazzanti M - Angew. Chem. Int. Ed. Engl. (2013)

Plots of a) χT vs. T and b) ln (χT) vs. 1/T for a polycrystalline sample of 2 measured at 0.05 T applied field.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232274&req=5

fig02: Plots of a) χT vs. T and b) ln (χT) vs. 1/T for a polycrystalline sample of 2 measured at 0.05 T applied field.
Mentions: Variable-temperature (2–300 K) magnetic susceptibility measurements were performed on polycrystalline samples of 1 and 2 in static magnetic fields ranging from 0.01 to 5 T (Figure 2 and the supplementary information). The measured χT value for 2 at room temperature is approximately 4.3 cm3 K mol−1; considering that the susceptibility curves for the Cd-based analogue 1 (see the Supporting Information) point towards a much smaller χT value (below 0.3 cm3 K mol−1) we can conclude that this value is in line with what is expected for one spin-only divalent manganese (with S=5/2 and g close to 2) and one pentavalent uranium ion, whose magnetic moment is significantly reduced with respect to the free-ion value by the combined effect of ligand field and covalent bonding.19 The χT product decreases with decreasing temperature to 4.1–4.2 cm3 K mol−1 at 150 K; the fact that the same quantitative behavior is observed for 1 and that the decrease is similar in absolute value for the two compounds, allows the attribution of this effect to the ligand-field state depopulation for the anisotropic uranium centers, whereas the contribution of the more isotropic manganese ions can be approximately regarded as constant within this temperature range. Below 150 K, the susceptibility of 2 increases to reach a field-dependent maximum, with values of 56.8 cm3 K mol−1 at 0.01 T (Figure S9) and 52.7 cm3 K mol−1 at 0.05 T (Figure 2), before dropping rapidly at very low temperatures owing to saturation effects, magnetic anisotropy, and possibly inter-chain antiferromagnetic interactions. The increase of χT below 150 K, as well as the strong deviation from the Curie–Weiss behavior of χ−1 vs. T (see the Supporting Information), suggests dominant ferromagnetic interactions leading to an aligned-spin ground state. None of this is observed for the Cd-based analogue 1, where only an abrupt decrease of the χT product below 25 K is observed, which is most likely due to single-ion crystal field effects associated with UV,8a quenching of the orbital angular momentum, and possibly weak next-nearest-neighbor antiferromagnetic exchange between uranium centers.

Bottom Line: The 5f-3d heterometallic 1D chains [{[UO2(salen)(py)][M(py)4](NO3)}]n, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO2(salen)py][Cp*2Co] (Cp*=pentamethylcyclopentadienyl) with Cd(NO3)2 or Mn(NO3)2 in pyridine.The infinite UMn chain displays a high relaxation barrier of 134±0.8 K (93±0.5 cm(-1)), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group.It also exhibits an open magnetic hysteresis loop at T<6 K, with an impressive coercive field of 3.4 T at 2 K.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Reconnaissance Ionique et Chimie de Coordination SCIB, UMR-E3 CEA-UJF, INAC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 09 (France) http://inac.cea.fr/Pisp/51/marinella.mazzanti.html.

No MeSH data available.


Related in: MedlinePlus