Reduced molybdenum phosphates: synthesis, characterization and magnetic properties

Lezama, Luís; Rojo, J. M.; Pizarro, J L; Arriortua, Marı́a I.; Rojo, Teófilo

doi:10.1016/0167-2738(93)90175-3

Cited by 10 publications

(8 citation statements)

References 23 publications

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“…For example, 1.4 μ B was found for La 2 LiMoO 6 , Ba 2 YMoO 6 , and Ba 2 LuMoO 6 , where quantum fluctuations are often cited as the origin of the moment reduction. One of these reports find a value closer to the spin-only value for Ba 2 YMoO 6 , and an effective moment of 1.69 μ B is reported for MoOPO 4 …”

Section: Results and Discussionmentioning

confidence: 54%

“…One of these reports find a value closer to the spin-only value for Ba 2 YMoO 6 , 23 and an effective moment of 1.69 μ B is reported for MoOPO 4 . 26 A Curie temperature of 22.3 K is estimated from the temperature dependence shown in Figure 2b. The Curie temperature is surprisingly high considering that the intermolecular Mo−Mo distances are all longer than 5.6 Å with no simple superexchange paths.…”

Section: ■ Introductionmentioning

confidence: 99%

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Ferromagnetic Spin-1/2 Dimers with Strong Anisotropy in MoCl₅

McGuire

Pandey

et al. 2019

Chem. Mater.

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The pentachloride MoCl 5 adopts several molecular crystal structures, all comprising isolated Mo 2 Cl 10 units with well-separated Mo−Mo magnetic dimers. Using magnetization measurements, single-crystal X-ray diffraction, and first-principles calculations, we confirm ferromagnetism with strong anisotropy below a Curie temperature of 22 K in α-MoCl 5 , and report a fifth polymorph, ϵ-MoCl 5 , that we find to be ferromagnetic below 14 K. Magnetization measurements indicate unquenched orbital moments antialigned with the spins. This is confirmed by first-principles calculations, which also predict an unusually strong magnetocrystalline anisotropy in α-MoCl 5 arising from spin−orbit coupling. An anisotropy field near 80 T is calculated, while a smaller but still substantial anisotropy field exceeding 12 T is realized experimentally. Further, increased anisotropy and Curie temperature are predicted when W is substituted for Mo. Similarly, strong magnetism and anisotropy are predicted for isolated Mo 2 Cl 10 molecules, indicating the potential for true molecular magnetism. Together, these results identify Mo 1−x W x Cl 5 as novel molecular crystals that combine spin 1/2 with strong magnetic anisotropy and exhibit surprisingly high Curie temperatures, considering their molecular nature.

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Section: Results and Discussionmentioning

confidence: 54%

Section: ■ Introductionmentioning

confidence: 99%

Ferromagnetic Spin-1/2 Dimers with Strong Anisotropy in MoCl₅

McGuire

Pandey

et al. 2019

Chem. Mater.

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“…In the infrared spectrum of ReO 2 (PO 4 ) (Table 4) bands at about 1190 cm –1 , 1155 cm –1 , 1082 cm –1 , and 1024 cm –1 are attributed to the P–O symmetric and asymmetric stretching vibrations of [PO 4 ] group 9,43. In agreement with the IR spectrum of Re 2 O 7 44 two bands at about 968 cm –1 and 942 cm –1 are assigned to the stretching vibrations (O=Re=O).…”

Section: Resultsmentioning

confidence: 76%

“…We tend to correlate the broad band of ReO 2 (PO 4 ) centered at 874 cm –1 to the antisymmetric stretching vibration ν as (Re–O–P). This assignment is backed by ν as (Re–O–Re) ≈ 850 cm –1 observed for Re 2 O 7 45,44 and ν as (P–O–P) ≈ 950 cm –1 as it is observed for many pyrophosphates 9,43,46. Bands in between 600 and 400 cm –1 can be assigned to deformation vibrations δ (O–P–O).…”

Section: Resultsmentioning

confidence: 99%

The First Phosphates of Heptavalent Rhenium

Islam

Glaum

Pelka

et al. 2013

Zeitschrift anorg allge chemie

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ReVIIO2(PO4) and (ReVII2O5)Sio2[Sit2O(PO4)6] were obtained from Re2O7 and P4O10 in sealed silica tubes (250 ≤ ϑ ≤ 400 °C). The crystal structures were solved and refined from X‐ray single crystal data (ReVIIO2(PO4): C2/c, Z = 24, a = 14.403(1) Å, b = 8.414(1) Å, c = 20.647(3) Å, β = 93.165(8)°, T = 123 K, 10352 ind. refl., 218 variables, 24 atoms in asymmetric unit, R1 = 0.041, wR2 = 0.106; (ReVII2O5)Sio2[Sit2O(PO4)6]: P$\bar{1}$, Z = 1, a = 7.8589(3) Å, b = 7.8609(3) Å, c = 10.8311(4) Å, α = 85.312(2)°, β = 73.078(2)°, γ = 60.075(2)°, T = 298 K, 2551 ind. reflections, 174 variables, 22 atoms in asymmetric unit, R1 = 0.078, wR2 = 0.208). The complex crystal structure of ReO2(PO4) can be derived from the ReO3 structure type. The crystal structure of the silicophosphate consists of distorted [Re2O11] dioctahedra (1.69 Å ≤ d(Re–O) ≤ 2.08 Å), [SiIVO6] octahedra, and [Sit2O(PO4)6]12– heteropolyanions. In ReO2(PO4) monomeric perrhenyl ions (ReO2)3+ (∠(Ot,Re, Ot) ≈ 101.5°) are formed. The silicophosphate (Re2O5)Sio2[Sit2O(PO4)6] contains dinuclear (Re2O5)4+ cations. 31P‐MAS‐NMR studies on ReO2(PO4) are in accordance with three independent sites of phosphorus. The results of 31P‐ and 29Si‐MAS‐NMR studies on (Re2O5)Sio2[Sit2O(PO4)6] are in agreement with three crystallographically independent sites for phosphorus and two sites for silicon.

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“…The additional bands at 867 and 839 cm\ can be explained by the presence of VPO OH groups and can correspond to the (VOP) stretching modes of diphosphovanadate group since they occur at intermediate positions between the vibrations ranges usually observed for VOV and POP bonds (25). The shoulder at 795 cm\ by consequence can be explained by the [V}(O" V)] couplings in the same units, by analogy with vanadyl diphosphates (21).…”

Section: Infrared Spectroscopy Studymentioning

confidence: 91%