Synthesis, structure and magnetic properties of the mixed metal oxide solids [{M(H2O)2}V2O6] (MZCo, Ni)

Two mixed-metal oxide solids [{Co(H2O)2}V2O6] (1) and [{Ni(H2O)2}V2O6] (2) have been prepared and characterized by infrared spectroscopy, thermogravimetric analysis, manganometric titration, variable temperature magnetic susceptibility measurements, and complete single crystal X-ray structure analyses. The isomorphous structures of 1 and 2 consist of three-dimensional frameworks composed of vanadium oxide chains cross-linked by {M(H2O)2O4} (MZCo, 1; MZNi, 2) units. The vanadium oxide chains are composed of corner sharing {VO4} tetrahedra. The compounds have good thermal stability and lose coordinated water molecules above 190 and 232 8C, respectively. The effective magnetic moments for 1 and 2 at 300 K are close to the values expected for non-interacting high-spin cobalt(II) and nickel(II) centers in octahedral ligand fields. Crystal data: 1, H4CoO8V2, orthorhombic space group Pnma, aZ5.568(2), bZ10.690(6), cZ11.832(5) A° , VZ704.3(7) A° 3, ZZ4, rcalcZ2.762 Mg mK3, R1Z0.0329; 2, H4NiO8V2, orthorhombic space group Pnma, aZ5.536(1), bZ10.633(2), cZ11.762(2) A ° , VZ692.3(3) A ° 3, ZZ4, rcalcZ2.808 Mg mK3, R1Z0.0160. q 2004 Elsevier B.V. All rights reserved