Hydrothermal syntheses, structures and properties of two 3-D organic–inorganic hybrid mixed-valent polyoxovanadates [Ni(en)2][VIV4VV2O14] and [Cu(en)2][VIV2VV3O12.5]

Two 3-D organic–inorganic hybrid mixed-valent polyoxovanadates [Ni(en)2][VIV4VV2O14] (1) and [Cu(en)2][VIV2VV3O12.5] (2) (en = ethylenediamine) have been hydrothermally synthesized and characterized by elemental analyses, IR spectra, X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. The common feature of 1 and 2 is that both exhibit the 3-D organic–inorganic hybrid framework. It should be pointed out that the 3-D hybrid architecture of 1 is constructed from planar 2-D vanadium(IV/V)–oxygen layers through [Ni(en)2]2+ bridges, whereas the 3D hybrid framework of 2 is built by wavy 2-D vanadium(IV/V)–oxygen layers via [Cu(en)2]2+ connectors. The magnetic properties of 1 have been investigated and 1 behaves as the dominant antiferromagnetic interactions within VIV centers.