Syntheses, Crystal Structures And Characterizations Of New Arsenic-Vanadates Templated By Organic Amines And Transition Metal Complex

In recent years, polyoxometalates has received great attention as a result of structural diversity and potential applications in the fields of material chemistry, selective adsorption, catalysis, and magnetism. The syntheses, structures and characterizations of new polyoxometalates not only have theoretical significance, but also have broad potential applications.In this work, eight new arsenic-vanadates templated by ethylenediamine, diethylenetriamine, tetramethylammonium hydroxide, and transition metal (Co, Zn, Cd) complex have been synthesized under hydrothermal conditions. Three new vanadates of 1D beeline-chained, 2D layered, and 3D porous structures templated by ethylenediamine, imidazole, and tetramethylammonium hydroxide have been synthesized, respectively. All the compounds have been characterized by X-ray single crystal diffraction, elemental analyses, IR spectrum, thermogravimetric analysis, fluorescence analysis, and magnetism measurement.(1) Two new arsenic-vanadate compounds [Co(C₄H₁₃N₃)₂]₂[As₈V₁₄O₄₂ (H₂O)]·3.5H₂O (1) and (C₂N₂H₉)2(C₂N₂H₁₀)[As₈V₁₄O₄₂]·2.33H₂O (2) have been hydrothermally synthesized successfully. The molecule structural analysis show that both compounds have the same discrete cluster anion [As₈V₁₄O₄₂]4-. Moreover, in the compound (1), the polyanions are connected through Van der Waals forces to generate the soft channels that are filled by the [Co(C₄H₁₃N₃)₂]²⁺ cations and water molecule. In the compound (2), water molecule and organic molecule are linking cluster anions to create the supramolecular assembly through the hydrogen bonding.(2) Two new arsenic-vanadate compounds [Co(C₄H₁₃N₃)₂]₂ [As₈V₁₄O₄₂ (SO₄)]·2H3O·8H₂O (3) and(C₂N₂H₁₀)3[As₈V₁₄O₄₂(SO₄)]·1.5H₂O (4) have been hydrothermally synthesized. The molecule structural analysis show that both compounds have the same [As₈V₁₄O₄₂(SO₄)]6- polyanion. Moreover, in the two compounds, water molecules, organic molecules and the polyanions form supramolecular structures through the hydrogen bonding, [Co(C₄H₁₃N₃)₂]²⁺ cations and water molecules are located in the center. (3) A new arsenic vanadium compound (NH4)2[N(CH3)4]4[β-As₈V₁₄O₄₂(SO₄)] (5) has been synthesized under hydrothermal conditions. The molecule structural analysis reveals that the compound is composed of discrete [β-As₈V₁₄O₄₂(SO₄)]6- polyanion, disordered NH₄⁺, [N(CH3)4]+ cations.(4) Two new arsenic vanadium compounds [Zn(phen)3]2[γ-As₈V₁₄O₄₂]·4H₂O (6) and [Cd(phen)3]2[γ-As₈V₁₄O₄₂]·2H₂O (7) has been synthesized under hydrothermal conditions successfully. The molecule structural analysis reveals that the two compounds have the same [γ-As₈V₁₄O₄₂]4- polyanion.(5) A new 2D arsenic-vanadate layers supported cobalt coordination complex [Co(en)2(H₂O)]{[Co(en)₂]₂As₈V₁₄O₄₂(SO₄)}·3H₂O (8) has been synthesized hydrothernally. The magnetic measurement indicates a weak antiferromagnetic exchange coupling within the molecular unit, which is deemed to attribute to the contribution of V4+ and Co2+.(6) Three new vanadate compounds of the formula (C₂N₂H₁₀)VO(OH)4 (9), (NH4)3(C3N2H5)V4O10 (10) and V(OH)3·0.97H₂O (11), have been synthesized by solvothermal method. Structural analyses reveal a 1D beeline chained structure which is consist of VO6 octahedra in (9). Compound (10) possesses a 2D V-O layered structure formed by VO5 square-pyramids, protonated imidazole and remaining NH₄⁺ cations are inserted between the layers. The 3D open framework of (11) with the pyrochlore type is consist of V12 and V4 SBUs (secondary building units).