Synthesis, structure and magnetic properties of the mixed metal oxide solids [{M(H 2O) 2}V 2O 6] (M=Co, Ni)

Abstract

Two mixed-metal oxide solids [{Co(H 2O) 2}V 2O 6] ( 1) and [{Ni(H 2O) 2}V 2O 6] ( 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(H 2O) 2O 4} (M=Co, 1; M=Ni, 2) units. The vanadium oxide chains are composed of corner sharing {VO 4} tetrahedra. The compounds have good thermal stability and lose coordinated water molecules above 190 and 232 °C, 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, H 4CoO 8V 2, orthorhombic space group Pnma, a=5.568(2), b=10.690(6), c=11.832(5) Å, V=704.3(7) Å 3, Z=4, ρ calc=2.762 Mg m −3, R 1=0.0329; 2, H 4NiO 8V 2, orthorhombic space group Pnma, a=5.536(1), b=10.633(2), c=11.762(2) Å, V=692.3(3) Å 3, Z=4, ρ calc=2.808 Mg m −3, R 1=0.0160.