Systematic Study of the Interaction Between VIV Centres and LnIII Ions in Well Defined {V2IVLnIII}{AsIIIW9O33}2 Sandwich-Type Clusters: Part 2

• Published in: Journal of cluster science 2013-12, Vol.24 (4), p.979-988
• Main Authors: Merca, Alice, Schnack, Jürgen, van Slageren, Joris, Glaser, Thorsten, Bögge, Hartmut, Hoeke, Veronika, Läge, Mechtild, Müller, Achim, Krebs, Bernt
• Format: Article
• Language: English
• Subjects: Acidification; Aqueous solutions; Catalysis; Cations; Chemistry; Chemistry and Materials Science; Crystal lattices; Ferromagnetism; Gadolinium; Inorganic Chemistry; Ligands; Magnetic permeability; Nanochemistry; Original Paper; Physical Chemistry; Polyoxometallates; Single crystals; Sodium; Structural analysis; Transition metals; Vanadium
• ISSN: 1040-7278; 1572-8862
• DOI: 10.1007/s10876-013-0588-x

The gadolinium (Gd) member of a new type of heteropolytungstates that contain one lanthanide and two transition metal ions in a triangular arrangement is reported. The compound NaK 6 Gd 0.33 [((VO) 2 Gd(H 2 O) 4 K 2 (H 2 O) 2 (Na)(H 2 O) 2 )(α-B-AsW 9 O 33 ) 2 ]·24H 2 O ( 1 ) was prepared from acidified aqueous solutions of Na 2 WO 4 ·2H 2 O, As 2 O 3 and VOSO 4 ·5H 2 O to which Gd 3+ ions were added. The single crystal X-ray structure analysis (monoclinic, space group P 2 1 / m ) shows that the anion consists of two [α-B-As III W 9 O 33 ] 9− trilacunary Keggin-type units linked by two VO 2+ , one Gd 3+ as well as weakly by two K + and one Na + ions, resulting in a sandwich-type structure with idealized C 2v symmetry. The problem of positioning crystal lattice and special polyoxometalate sites with different cations is discussed also in connection with supramolecular chemistry aspects and as an option for further research. A fit of the magnetic susceptibility yielded exchange coupling constants of J VV  = −2.55 cm −1 (anti-ferromagnetic) between the vanadium ions and J GdV  = 0.6 cm −1 (ferromagnetic) between the Gd and each of the two vanadium ions. The complete magnetochemical analysis also revealed a partial occupancy of the Na + sites in the counter-cation–water system by Gd 3+ ions (0.33 Gd 3+ ions in total).