Superexchange pathways in oxovanadium(IV) phosphates

Amorós, Pedro; Beltrán, Antonio; Beltrán, Daniel

doi:10.1016/0925-8388(92)90658-v

Cited by 11 publications

(5 citation statements)

References 21 publications

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“…The O−P−O bridges enhance the Δ e − Δ e 0 value for the intrachain and interchain bridged spin dimers. This is consistent with the observation that in oxovanadium phosphates the O−P−O bridges provide spin exchange pathways. , However, the enhancement of Δ e − Δ e 0 by the O−P−O bridges is nearly the same for the intrachain and interchain bridged spin dimers (about 24 meV). Furthermore the Δ e − Δ e 0 value is larger for the intrachain than for the interchain bridged spin dimer even in the absence of the O−P−O bridges.…”

Section: Resultssupporting

confidence: 90%

“…Thus, a number of important questions remain unanswered. It is known that the O−P−O bridges of oxovanadium phosphates provide spin exchange pathways and the way these bridges are arranged determines the magnitude of the spin exchange interaction. , However, it is not clear why the spin exchange via the O−P−O bridges is much larger within each dimer chain than between adjacent dimer chains. As already mentioned, the dimer chains of HPO and APO are well described by the spin- 1 / 2 alternating AFM chain model. − However, it is not known which spin exchange interaction, the one via the PO 4 tetrahedra or that within a V 2 O 8 dimer, is larger in magnitude.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Spin Exchange Interactions in the Three Phases of Vanadium Pyrophosphate, (VO)₂P₂O₇, in Terms of Spin−Orbital Interaction Energy

2000

Inorg. Chem.

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The spin exchange interactions in the ambient-pressure orthorhombic (APO), high-pressure orthorhombic (HPO), and ambient-pressure monoclinic (APM) phases of the vanadium pyrophosphate, (VO)2P2O7, were analyzed by calculating the spin-orbital interaction energies delta e-delta e0 of their spin dimers. The anisotropy of the spin exchange interactions in the HPO phase is well explained by the delta e-delta e0 values. For the APO phase, the reported crystal structure does not provide accurate enough delta e-delta e0 values to conclude unambiguously which of the V1-V2 and V3-V4 chains has a larger spin gap and which of the bridged and edge-sharing spin dimers has a stronger spin exchange interaction in the V1-V2 and V3-V4 chains. The APM phase is predicted to exhibit essentially two spin gaps, with a large spin gap for the V8-V5-V7-V6 chain and a very small one for the V4-V2-V3-V1 chain.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Analysis of the Spin Exchange Interactions in the Three Phases of Vanadium Pyrophosphate, (VO)₂P₂O₇, in Terms of Spin−Orbital Interaction Energy

2000

Inorg. Chem.

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“…In general, oxovanadium(IV) phosphates exhibit magnetic behaviors that cannot be deduced exclusively from their overall structural features. This is because of the involvement of phosphate bridges in the spin transfer between V(IV) centers . For example, the 2D materials (NH 4 )VOPO 4 78 and β-VO(HPO 4 )·2H 2 O 79 and the 3D phase VO(H 2 PO 4 ) 2 79 exhibit magnetic properties consistent with the Heisenberg antiferromagnetic chain model…”

Section: Resultsmentioning

confidence: 98%

Evolution of the Structural Chemistry of Vanadium Organodiphosphonate Networks and Frameworks: Structural Consequences of Fluoride Incorporation in the Development of Stable Phases with Void Channels

Ouellette

O’Connor

et al. 2006

Inorg. Chem.

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Hydrothermal reactions of solutions containing a vanadate source, an organodiphosphonate, an organonitrogen component, and HF (V/P/O/F) yield a series of oxyfluorovanadium-diphosphonates with charge-compensation provided by organoammonium cations or hydronium cations. While V/P/O/F networks provide the recurrent structural motif, the linkage between the layers and the details of the polyhedral connectivities within the layers are quite distinct for the five structures of this study. [H2pip][V4F4O2(H2O)2{O3P(CH2)3PO3}2] (1) (pip = piperazine) is a conventional three-dimensional (3D) "pillared" layer structure, whose V/P/O/F networks are buttressed by the propylene chains of the diphosphonate ligands. In contrast, [H2en][V2O2F2(H2O)2{O3P(CH2)4PO3}] (2) and [H2en]2[V6F12(H2O)2{O3P(CH2)5PO3}2 {HO3P(CH2)5PO3H}] (3) are two-dimensional (2D) slablike structures constructed of pairs of V/P/O/F networks sandwiching the pillaring organic tethers of the diphosphonate ligands. Despite the common overall topology, the layer substructures are quite different: isolated {VO5F} octahedra in 2 and chains of corner-sharing {VO(3)F(3)} octahedra in 3. The 3D structure of [H2en]2[V7O6F4(H2O)2{O3P(CH2)2PO3}4].7H2O (4.7H2O) exhibits a layer substructure that contains the ethylene bridges of the diphosphonate ligands and are linked through corner-sharing octahedral {VO6} sites. The connectivity requirements provide large channels that enclose readily removed water of crystallization. The structure of [H3O][V3F2(H2O)2{O3P(CH2)2PO3}2].3.5H2O (5.3.5H2O) is also 3D. Because of the similiarity with 4.7H2O, it exhibits V/P/O/F layers that include the organic tethers of the diphosphonates and are linked through corner-sharing {VO6} octahedra. In contrast to the network substructure of 4.7H2O, which contains binuclear and trinuclear vanadium clusters, the layers of 5.3.5 H2O are constructed from chains of corner-sharing {VO4F2} octahedra. Thermal studies of the open framework materials 4 and 5 reveal that incorporation of fluoride into the inorganic substructures provides robust scaffoldings that retain their crystallinity to 450 degrees C and above. In the case of 4, dehydration does not change the powder X-ray diffraction pattern of the material, which remains substantially unchanged to 450 degrees C. In the case of 5, there are two dehydration steps, that is, the higher temperature process associated with loss of coordinated water. This second dehydration results in structural changes as monitored by powder X-ray diffraction, but this new phase is retained to ca. 450 degrees C. The materials of this study exhibit a range of reduced oxidation states: 1 is mixed valence V(IV)/V(III) while 2 and 4.7H(2)O are exclusively V(IV) and 3 and 5.3.5H2O are exclusively V(III). These oxidation states are reflected in the magnetic properties of the materials. The paramagnetism of 1 arises from the presence of V(III) and V(IV) sites and conforms to the Curie-Weiss law with C = 2.38 em K/(Oe mol) and = -66 K with mu(eff) (300 K) = 4.33 mu(B). Compounds 3-5 ...

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“…The source for this confusion is rather complicated superexchange pathways between V> spins which were di$cult to assume straightforwardly by taking only the V>}O sublattice into consideration. The importance of superexchange interactions through phosphate groups had been pointed out by Beltran and his co-workers in their systematic studies on various oxovanadium(IV) phosphates (9,10). In fact, according to the inelastic neutron scattering experiments (7), the largest interaction J in (VO) P O was found between VO square pyramids bridged by PO tetrahedra and the second largest interaction J between edge-sharing VO pyramids.…”

Section: Introductionmentioning

confidence: 97%

Structural Study of the Quantum-Spin Chain Compound (VO)2P2O7

Hiroi

Azuma

Fujishiro

et al. 1999

Journal of Solid State Chemistry

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Superexchange pathways in oxovanadium(IV) phosphates

Cited by 11 publications

References 21 publications

Analysis of the Spin Exchange Interactions in the Three Phases of Vanadium Pyrophosphate, (VO)₂P₂O₇, in Terms of Spin−Orbital Interaction Energy

Analysis of the Spin Exchange Interactions in the Three Phases of Vanadium Pyrophosphate, (VO)₂P₂O₇, in Terms of Spin−Orbital Interaction Energy

Evolution of the Structural Chemistry of Vanadium Organodiphosphonate Networks and Frameworks: Structural Consequences of Fluoride Incorporation in the Development of Stable Phases with Void Channels

Structural Study of the Quantum-Spin Chain Compound (VO)2P2O7

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Superexchange pathways in oxovanadium(IV) phosphates

Cited by 11 publications

References 21 publications

Analysis of the Spin Exchange Interactions in the Three Phases of Vanadium Pyrophosphate, (VO)2P2O7, in Terms of Spin−Orbital Interaction Energy

Analysis of the Spin Exchange Interactions in the Three Phases of Vanadium Pyrophosphate, (VO)2P2O7, in Terms of Spin−Orbital Interaction Energy

Evolution of the Structural Chemistry of Vanadium Organodiphosphonate Networks and Frameworks: Structural Consequences of Fluoride Incorporation in the Development of Stable Phases with Void Channels

Structural Study of the Quantum-Spin Chain Compound (VO)2P2O7

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Analysis of the Spin Exchange Interactions in the Three Phases of Vanadium Pyrophosphate, (VO)₂P₂O₇, in Terms of Spin−Orbital Interaction Energy

Analysis of the Spin Exchange Interactions in the Three Phases of Vanadium Pyrophosphate, (VO)₂P₂O₇, in Terms of Spin−Orbital Interaction Energy