Sandwich-type polyoxotungstate hybrids decorated by nickel-aromatic amine complexes

Abstract

Three new sandwich-type polyoxotungstates (POTs) decorated by nickel-2,2′-bpy complexes [{Ni(2,2′-bpy) 2(H 2O)} 2{Ni(2,2′-bpy)} 2 {Ni 4(H 2O) 2(B- α- XW 9O 34) 2}] n− ( X=P V, n=4 for 1; X=As V, n=4 for 2; X=Ge IV, n=4 for 3) (2,2′-bpy=2,2′-bipyridine) were successfully synthesized under hydrothermal conditions and structurally characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction, and magnetic properties. Single-crystal structural analyses indicate that 1 and 2 are isostructural and both crystallize in the monoclinic space group C2 /c, whereas 3 belongs to the triclinic space group P 1 ¯ . To our knowledge, 1, 2 and 3 represent rare examples of the organic–inorganic hybrid sandwich-type polyoxometalates functionalized by multiple nickel-aromatic amine complexes. Magnetic measurements of 1 exhibit the presence of ferromagnetic interactions within the rhombic tetranuclear-Ni II cluster.