Influence of metal ions on the structures of Keggin polyoxometalate-based solids: Hydrothermal syntheses, crystal structures and magnetic properties
- Institute of Polyoxometalate Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China)
- Instituto de Ciencia Molecular, Universidad de Valencia. Pol. La Coma s/n 46980 Paterna, Valencia (Spain)
Three new Keggin polyoxometalate (POM)-based compounds linked to 3d metal complexes have been synthesized under hydrothermal conditions: [Cu(phen){sub 2}]{sub 2}{l_brace}[Cu(phen)]{sub 2} [SiMo{sub 12}O{sub 4}(VO){sub 2}]{r_brace} (1), {l_brace}[Zn(phen){sub 2}]{sub 2}[GeMo{sub 12}O{sub 4}(VO){sub 2}]{r_brace}{l_brace}[Zn(phen){sub 2}(H{sub 2}O)]{sub 2} [GeMo{sub 12}O{sub 4}(VO){sub 2}]{r_brace}.3H{sub 2}O (2) and {l_brace}[Co(phen){sub 2}]{sub 2}[PMo{sub 12}O{sub 4}(VO){sub 2}]{r_brace}{l_brace}[Co(phen){sub 2}(OH)]{sub 2} [PMo{sub 12}O{sub 4}(VO){sub 2}]{r_brace}.2.5H{sub 2}O (3) (phen=1,10-phenanthroline). These three compounds present, as building blocks, the bicapped Keggin anions [XMo{sub 12}O{sub 4}(VO){sub 2}] (X=Si, Ge and P). Compound 1 consists of a bicapped Keggin anion [SiMo{sub 12}O{sub 4}(VO){sub 2}]{sup 2-} linked to two [Cu(phen)]{sup +} complexes with two [Cu(phen){sub 2}]{sup +} countercations. Compound 2 contains two bicapped Keggin anions [GeMo{sub 12}O{sub 4}(VO){sub 2}]{sup 4-}, one linked to two [Zn(phen){sub 2}(H{sub 2}O)]{sup 2+} cations and the other one linked to two [Zn(phen){sub 2}]{sup 2+} cations. Compound 3 is a two-dimensional POM-based square network formed by bicapped Keggin anions [PMo{sub 12}O{sub 4}(VO){sub 2}]{sup 4-} connected by [Co(phen){sub 2}]{sup 2+} cations. Discrete bicapped Keggin anions [PMo{sub 12}O{sub 4}(VO){sub 2}] linked to two [Co(phen){sub 2}(OH)]{sup +} cations are located between the layers. The magnetic properties show the presence of antiferromagnetic interactions among the reduced Mo(V) atoms (in the three compounds) plus a paramagnetic contribution from the V(IV) atoms (in 1 and 2). Compound 3 shows, in addition, an antiferromagnetic interaction between the Co(II) and the V(IV) ions directly linked through an oxygen bridge. The low-temperature ESR spectra of compound 3 confirm the presence of the reduced Mo(V) ions and the antiferromagnetic coupling between the Co(II) and the V(IV) ions. -- Graphical abstract: Three new Keggin polyoxometalate-based compounds have been synthesized under hydrothermal condition. These three compounds present the bicapped Keggin anions [XMo{sub 12}O{sub 4}(VO){sub 2}] (X=Si, Ge and P) as building blocks. Among the three compounds, compound 3 is a two-dimensional polyoxometalate-based square network formed by bicapped Keggin anions [PMo{sub 12}O{sub 4}(VO){sub 2}]{sup 4-} connected by [Co(phen){sub 2}]{sup 2+} cations. Discrete bicapped Keggin anions [PMo{sub 12}O{sub 4}(VO){sub 2}] linked to two [Co(phen){sub 2}(OH)]{sup +} cations are located between the layers.
- OSTI ID:
- 20784856
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 1; Other Information: DOI: 10.1016/j.jssc.2005.09.051; PII: S0022-4596(05)00438-X; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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