Unprecedented cyclic [Mo6O19]2−cluster and five organic–inorganic hybrids based on polyoxomolybdates and 4-amino-3,5-bis(pyridyl)-1,2,4-triazole

Abstract

Five novel hybrid compounds, [Mo₈O₂₆Cu₂(4-abpt)₂]_n·4nH₂O (1), (4-H₂abpt)₂[Mo₈O₂₆] (2), [Mo₈O₂₆Cu₂(3-abpt)₂(H₂O)₂]_n (3), [MoO₄Cu(3-abpt)(H₂O)]_n (4), and [Mo₆O₁₉Co(3-abpt)₂]_n·4nH₂O (5) were prepared by reacting MoO₃/(NH₄)₆Mo₇O₂₄ with 4-amino-3,5-bis(3/4-pyridyl)-1,2,4-triazole (3/4-abpt) and corresponding metal salts. Compound 1 is a 2D coordination polymer containing extended γ-[Mo₈O₂₆]⁴⁻ and [Cu₂(4-abpt)₂]⁴⁺ ribbons. Compound 2 is a supramolecular hybrid aggregate composed of H-bond linking β-[Mo₈O₂₆]⁴⁻ and 4-H₂abpt²⁺. Compound 3 exhibits a 2D rectangular network constructed by isolated β-[Mo₈O₂₆]⁴⁻clusters and [Cu₂(3-abpt)₂]⁴⁺. In compound 4, each MoO₄²⁻ anion links two Cu(II) ions to form a S-type [CuMoO₄]_n chain, which is further linked by bidentate 3-abpt to form a 2D wave-like network. In complex 5, unprecedented cyclic [Mo₆O₁₉]²⁻cluster links two neighbouring hexamolybdates and two Co(II) ions to form a 2D [CoMo₆O₁₉]_n network, which is further pillared by tetradentate 3-abpt to generate a 3D metal–organic framework. These compounds are thermally stable under 250 °C. The composites of the final residues were analyzed by PXRD.