Magnetic properties of vanadium(IV)-based extended systems: [(VO)3(μ-PO4)2(2,2′-bpy)(μ-OH2)]·1/3H2O and (VO)2H4P2O9

The magnetic properties of [(VO)3(μ-PO4)2(2,2′-bpy)(μ-OH2)]1/3H2O (1) and (VO)2H4P2O9 (2), a tubular and a layered VIV phosphates containing triply oxido bridged VIV dimers, are analyzed. In compound 1 the presence of an additional VIV connected with the VIV dimers through μ1,2-PO43− bridges is desc...

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Published in:Inorganica Chimica Acta 2013-01, Vol.395, p.176-180
Main Authors: Venegas-Yazigi, D., Muñoz, K., Saldías, M., Valdés de la Barra, K., Vega, A., Paredes-García, V., Gómez-García, C.J., Le Fur, E., Cañón-Mancisidor, W., Spodine, E.
Format: Article
Language:English
Subjects:
Chemical Sciences
DFT
Hybrid materials
Material chemistry
Molecular magnetism
Vanadium
VPO
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Summary:The magnetic properties of [(VO)3(μ-PO4)2(2,2′-bpy)(μ-OH2)]1/3H2O (1) and (VO)2H4P2O9 (2), a tubular and a layered VIV phosphates containing triply oxido bridged VIV dimers, are analyzed. In compound 1 the presence of an additional VIV connected with the VIV dimers through μ1,2-PO43− bridges is described with a Curie–Weiss type correction. The moderate antiferromagnetic coupling found in both compounds is justified from the structural parameters of the bridges. [Display omitted] ► Tubular and layered structures. ► Phosphate bridges. ► VIV spin carriers. ► Antiferromagnetic. The magnetic properties of [(VO)3(μ-PO4)2(2,2′-bpy)(μ-OH2)]1/3H2O (1) and (VO)2H4P2O9 (2), a tubular and a layered vanadium(IV) phosphates containing triply oxido bridged VIV dimers, are analyzed considering the Bleaney–Bowers S=1/2 dimer model. In compound 1 the presence of an additional VIV connected with the VIV dimers through μ1,2-PO43− bridges is described with a Curie–Weiss type correction. This model reproduces the magnetic properties of compound 1 with g=1.956, Jdim=−102.1cm−1, θ=−0.4cm−1 and Nα=278×10−6emumol−1. In compound 2, the presence of a small percentage of paramagnetic impurity has to be considered to account for the divergence of χm at low temperatures. This simple model reproduces the magnetic data of compound 2 with g=1.99, J=−62.4cm−1 and a 1.2% of monomeric impurity. The moderate antiferromagnetic coupling found in the triply oxido bridges VIV dimers is justified from the structural parameters of the bridge. These studies confirm that the coupling through –O–P–O– bridges is antiferromagnetic and relatively weak, as well as previous magneto-structural correlations in this kind of oxido bridges. DFT calculations on a dinuclear fragment model for the two systems gave the following values of Jcalc=−72.4cm−1 for 1 and Jcalc=−5.2cm−1 for 2. These values reproduce the antiferromagnetic nature of the superexchange interactions between the VIV centers.
ISSN:0020-1693
1873-3255
0020-1693
DOI:10.1016/j.ica.2012.10.024