Two novel polyoxotantalates formed by Lindqvist-type hexatantalate and Copper-amine complexes

Two novel polyoxotantalate derivatives, {[Cu(1,3-dap)₂] ₂[Cu(1,3-dap)(H₂O)]₂[Ta₆O ₁₉]}•8H₂O (1) and [Cu(en)₂] ₄[Ta₆O₁₉]•14H₂O (2) (1,3-dap = 1,3-diaminopropane, and en = ethylenediamine), which are constructed from the Lindqvist-type [Ta₆O₁₉]^8- anion and copper-amine complexes, have been synthesized and characterized by elemental analyses, IR, XPS, TGA and single-crystal X-ray diffraction. In compound 1, each [Ta₆O₁₉]^8- anion is bound to four copper fragments via the surface bridging oxygen atoms to form a neutral tetrasupported Lindqvist structure, which is further connected by water trimer via hydrogen-bonds to yield a one-dimensional (1D) supramolecular chain. In compound 2, the [Ta₆O₁₉]^8- anions are linked together via the hydrogen bonds and Cu-O weak interaction to form an infinite 1D supramolecular chain, which is further connected to each other via hydrogen bonds with the cyclic water tetramer to yield a two-dimensional (2D) supramolecular network.