Hydrothermal syntheses, structures and magnetic properties of coordinationcation metavanadates, Cu(tn)(2)(VO3)(2) and Ni(NH3)(2)(VO3)(2)

Two new metavanadates, Cu(tn)(2)(VO3)(2) (tn = 1,3-diaminopropane) and Ni(N H3)(2)(VO3)(2), have been prepared under hydrothermal conditions and their single-crystal structures determined by X-ray diffraction. Both structures consist of corner-sharing VO4 tetrahedral chains with complex cations occup ying the interchain positions. While there dominantly exist electrostatic i nteractions between the Cu(tn)(2)(2+) fragments and the vanadium oxide chai ns in Cu(tn)(2)(VO3)(2) the Ni(NH3)(2)(2+) moieties in the Ni(NH3)(2)(VO3)( 2) bridge the vanadium oxide chains into a three-dimensional framework stru cture by Ni-O covalent interactions. The magnetic properties were measured in the temperature ranging from 4 to 275 K. It is shown that Cu(tn)(2)(VO3) (2) possesses well-separated Cu2+ centers and that the magnetic behavior of Ni(NH3)(2)(VO3)(2) can be explained based on a one-dimensional Ising model . (C) 2000 Elsevier Science B.V. All rights reserved.